Saving Underscan settings

Hello Swim-a-thon,

It sounds like you're changing the underscan settings for your Mac mini, but the settings are changing back as you use your device, correct? We'd like to help.

Are you using the steps on the following page to adjust the underscan settings? About overscan and underscan on your Mac, Apple TV, or other display

If you are using the steps in the above link, do the changes seem to revert after using the device for a certain amount of time, or does it seem to happen randomly?

Also, to help narrow this behavior down further, would you mind confirming which macOS version your device is running? Find out which macOS your Mac is using

Thanks!

Yes, my old (now dead) Mac Mini 2012 kept the correct under-scan setting for my TV monitor, but when I switched to a new Mac Mini M1 this year I found that it lost the under-scan setting and always reset to no under-scan when I switched to TV, SCART or another HDMI input on the TV monitor. 

What I found out was, that I could set the under-scan correctly on the Mac and then use the Television HDMI setting for the Mac channel (HDMI 1 in this case) and then set the TV "Aspect Ratio" to "Point To Point" (instead of 4:3 or 16:9 or Zoom).  

Then it no longer mattered that the Mac always reset to Zero Under-scan.  

I agree that it would be better (more expected) if the Mac could remember the correct under-scan setting, but the TV very kindly solved the problem for me, in my case.