Garmin gives you multiple mounts with most of their devices and a slew of o-rings to fasten them on. Why are you swapping mounts? If you don't have the right mount for all your bikes, then get multiple mounts so you aren't constantly stretching and relaxing the o-rings and subjecting them to wear, abrasion and nicks.
Most everything Garmin on a bicycle uses a 1/4 turn mount. Garmin makes all sorts of variations of that mount to fit bars, stays, seat post or where ever you want to put them. And many third party vendors have their own version of the Garmin 1/4 turn mount that is even more inexpensive or more costly depending on what you want.
Don't be switching mounts from bike to bike.