switching screens

Hi, I am working between a Microsoft Office 2019 (win) and Libreoffice (mac). When I switch with the trackpad between the two and I am back in the Microsoft Office 2019 (win), if I press cmd + F to perform a search, this command is not applied to the last used program within Windows. It produces...

I am running Win XP on Parallels (got some old, but indispensable programs which need XP). After I open Parallels and then a folder or a file, the Win screen flips back to the Mac screen without me doing anything. Sometimes it flips back by itself after the file has been opened, mostly it does...