So I was trying out another PDF reader just for the hell of it, and was confused about highlighting (There was a tool in the ribbon bar that I was too stupid to use).
Instead of looking through documentation, I actually tried to use the built-in AI to see what wisdom it could offer a peasant like me.
On the same subject, are there any open source PDF readers you can recommend?
Okular from the KDE Project is pretty good imho. It's cross platform. https://okular.kde.org/