Result and one-line proposed solution:
User-specific settings, `settings.matlab.desktop.DisplayScaleFactor`in particular, in MATLAB R2021a are not saved in R2021a. This setting seems to be correctly addressed in other versions, such as R2019b (tested) and R2020a (shown in the url below).
Test platform:
MATLAB R2021a on Ubuntu 20.04 LTS (and MATLAB R2019b on the same OS for comparison)
Details:
I found this issue because I was seeking for the high DPI solution for MATLAB R2021a. I found a related question as listed below. I tried the suggested solution, which seems to work perfectly on MATLAB R2020a. However, it does not work on my side.
s = settings;s.matlab.desktop.DisplayScaleFactor
s.matlab.desktop.DisplayScaleFactor.PersonalValue = 2
At first, I thought it might be the OS, since I am using the relatively new fractional scaling feature of Ubuntu 20.04 to better use 4K monitors. Out of curiosity, I tried R2019b on the same computer and it worked perfectly. Then I realize that the issue might be that R2021a forgot to write the display factor setting to the user directory (instead of global setting which requires sudo in Linux because I do not need sudo to change this setting). Then I compare `~/.matlab/R2021a` and `~/.matlab/R2019b` and eventually found that in `matlab.mlsettings/fsroot/settingstree/matlab/display/settings.json`, new setting `DisplayScaleFactor` was not saved. By comparing it with the value in `~/.matlab/R2019b`, I added
{"attributes":{"readonly":false,"runtimeDefaultFcn":{},"settingValueValidator":{},"validationFcn":{},"visible":true},"hasValue":true,"isUserDefined":false,"isVector":false,"name":"DisplayScaleFactor","value":"2"}
in the settings string and save it, it turned out to be solved perfectly.
Related question:
