mine did the same thing when i first had them for about the first year but i was messing around with the wiring and they started changing colors i think they had a bad ground but not positive but my fuel pressure guage and boost guage both quit so think im just going to order new guages

Tried today with moving the ground to a better spot, didnt help, only tried on the fuel pressure gauge. I also switched over the constant power and switch power to see if that would help and nothing happened. Oh well...

i have glow shift guages and found that the instruction can be found on their web site,make sure you followed the instructions to the T.
They also have tech support and you can give them a call. Otherwise about the guages i did have problems with one and had to send it back - they did send another a couple days later.

my only complaint is there too bright at night when plowing or driving through the mountains

Ive had the GlowShift EGT, Trans, & Boost gauges for a couple of years now. Wish I bought better ones, but budget didnt permit at the time & I really needed gauges to monitor while towing my new travel trailer. But, my EGT gauge sometimes changes to red and stays on red for a few days and pushing the button does nothing. I originally set to green when new. Plus sometimes it changes to blue or yellow on its own, momentarily, then back to green. Drives me Freaking crazy sometimes! "You get what you pay for" rings in my head when this happens. The other two gauges are behaving themselves, so far. I will replace with ISSPRO gauges in the near future.