Are you sure.....?
The following rant has nothing to do with the device in question - I have no idea?(Though I like the "You're going backwards, no matter what your "analog" compass says. A compass only knows North(If you're lucky?). A GPS knows which way you're going.). If the unit in question has an "actual" compass IN IT, it may be affected by magnets, metal, etc. But here, sounds like your GPS said you were going backwards. Look Out Behind You!
Even if an answer is found for this case, I recommend, with anything new or otherwise unknown(Even if it's old), to - Start At The Beginning.
One more "thought", before diving in. If any electronic/computerized device has a problem - particularly a problem it "didn't have yesterday...", the first thing to try is to reboot/restart/turn-off, then back on, unplug, re-plug the device(Whatever "resets" the device without changing any settings or deleting any data - the procedure, often called "soft reset", is in the manual, isn't it? I don't know.). Works about 99.99 percent of the time.
If that doesn't help, and you never did(Or didn't do all) the following(And more I can't remember, myself, at the moment - I should be mowing the lawn or something, but this is more fun...), let's give some of this stuff a try...
From the top:
Download manual for the unit, prior to purchase - read same, carefully. Ask questions on forums, of sales folks or the manufacturer, if needed. Be v-e-r-y familiar with what you are going to buy, before you buy it. 40 years ago this could be tough. Now, with everything you need to know just a click or two away, on computer, tablet or phone, there are no excuses - we can do our research, therefore we must.
After acquiring a new "thing", in this case an electronic thing:
Pull-up, on computer(Or get out, if you bothered to print) the manual.
Open box - pull out device, checking that it's all there, and in(At least visually) good shape.
Find(Or acquire) any cabling needed to hook device to computer(You may need a "real" computer for this?). If you find you don't need it now, you will. Keep it in an easy to find place. Keep all packaging materials(Found a really great USB cable in a keyboard box, 3 months after I bought the thing - it was taped under the fancy cardboard insert the keyboard was laying in - it was supposed to be "in there" - and it was...).
Go to the manufacturer website. Find any updated software or firmware(Or manual addendums, etc.). Install same, following manufacturers instructions exactly.
This unit's last update was July 6, 2015... Yes? No?
After verifying proper updates(If any), begin to explore the unit(Best done at home, in a quiet space, with plenty of time and energy.). You may not be able to do everything, however, you can "get knowledgeable", and, set-up most settings. May take several "evenings"? Sooo much "stuff" in any device! Check for updates of all devices often.
This widget has a 30 page manual - with a lot of words.
The hardest part of a new device('Cause we really are so anxious to go use the thing!) is going through each and every setting - learning what they all mean - whether you need to change any settings - changing settings - making sure they actually changed - knowing if changing a setting "here", causes other changes "there".
Aside: Far as ANY new thing, these days - unless it's very new(Being an "early adopter" is not advised for something that you may really need to "work", now!). If you have ANY problem you can't seem to find an answer for --- Type the question you have(In exactly your words, first, though, you may have to revise, several times, your actual words, to get to "your" answer.) into your favorite search engine and see what others say. Careful! Anyone can write anything on the internet(I am!). Still, there is a wealth of wonderful information "out there" on almost any question we have. Often not "in depth"(Books and Libraries are for that.), but "little questions", some discussion - yes.
Always remember - There are good writers. There are good answers. The two do not always meet. Won't take much time to find spots with generally reliable answers(SBO.Com seems a good spot, to me.), but one still must "pick & choose" one's answers, as always. I look for sites/authors who seem to agree with what I believe I already know, then attempt to give them the benefit of the doubt for maybe knowing more than I do - but be careful. Don't bet the boat(Or farm) on an uncertain internet answer.
Caution! If NO ONE seems to have any idea of YOUR question??? Stop, and go to the manufacturer. You may have an issue that is rare/new/unknown(Yet?). Or, you may be completely wrong about the question in the first place!(Happens often to me... "Oh, that's what it means..! OK...").
Some settings or operation/testing, may have to wait for actual installation. Go as far as you can go "in home".
Install the device - perfectly, according to instructions(You already researched, in advance of purchase, that this could be done, right?). Still, if you, later, find you cannot install as COMPLETELY recommended, call the manufacturer for recommendations. This "thing" still may(Or not) work for you...
All installed, all correct, all "set", all functioning - go try it in it's planned use. Actually, only in "close" to planned use... Do not count on this thing until you've tested it - in this case "at the dock", then, in calm- unhurried waters. Not on your only 2 weeks on the water for the whole year. Not as the storm is bearing down. Try to do so at a time when you have internet(And something to get on the internet with, easily, legibly - your tiny smart phone may not seem so smart if you really need to read what's on the screen.) and --- when the manufacturer may answer the phone... On the water is no time to even try to do a Sunday, 7:30AM "chat"...
Aside: Try, prior to purchase, getting to the manufacturer tech support and asking questions. If you find EXCELLENT help, easily acquired, wonderful! If not? Go elsewhere. These days, Tech Support is the #1 reason to buy "this" over "that". All the best "specs" and gold-plated cases are meaningless, if Tech Support is hard to get or of poor quality. As long as it works, the device can be dealt with. Poor or No TS must bust the deal, before it is made.
Devices are simple. It's the multitude of settings and options and "features" that can be too hard to even try to bother with them all. Just because a manufacturer "can" throw this or that "in there" is no excuse to do so. Manufacturers are having a really hard time learning this. Customers are, meanwhile, buried in multi-multi-multi functions they've never even heard of, let alone need. I wish you well...
All I got, now. Dogs are hollering in the back yard. I have my own device investigations to pursue. Planning a complete throw-out and upgrade of my entire voiceover recording studio, with a limited budget. Got to do it. My fancy gear is older than my grand child, who is now in 9th. grade...... Alright, much of my stuff is older than my 20 year old grand child - sigh... I bought right - after long research. So right that it still works great, but, when it fails(Surely during an important gig - they're all important.) none of it can be replaced --- really old. The 2 ancient, tiny, sailboats on my limited property(My neighbors are getting restless.), and the old pop-up camper, all in need of serious work, will have to continue to wait. Will try to do a Dwyer order this week(I said that last week?)... Big Sigh... Have fun with your gadget - looks very cool. Still...... I bet, if it's a GPS, seemingly running "fine", it knows which way you're going...... There is a sign near me, in front of a church. It says: "Are you sure you're on the right road?" I've been seeing that sign for 30+ years, and I still don't know. I hope you do. Have fun!
Teddy G.
www.teddygvo.com