In the last version of Mathematica (12.2), some genius on Wolfram thought that is was a good idea to change the keyboard shortcut Ctrl+4, that have been there for years, so now users get a (broken) box to input TeX (doesn't work in my system) instead of an underscript.
It's possible, but really annoying, to enter underscripts entering an overscript (Ctrl+7) and switching to underscript (Ctrl+5), then deleting the overscript.
This change also breaks the documentation of
Underscript, by the way.
Is there a way to configure the notebook and remap the shortcut to the older one?