My new computer has been set up with Windows on the main drive, and Ubuntu 21.04 on a 250 gb expansion card.
by changing the boot timeout from zero to two seconds, it’s easy to catch the F12 boot override to switch.
The question is, when I switch back to boot Windows, after using Ubuntu, the Time has reset to match UTC. The time zone is still set to my local time. I have to consciously sync the time. to get it correct.
Note that you can also change Windows to use UTC for the RTC - I haven’t looked up how to do this in a while, but I believe it’s a registry setting. You might prefer to do this instead if you have multiple Linux installs, or if you prefer reinstalling Linux instead of upgrading to the latest version.