Should I Uninstall/ReInstall?

As I posted before I had a problematic first installation (set up by Microsoft Technical Help controlling my computer). I wasn’t sure which drives the content had gone to (still not!!) but the Windows App "Move"feature is only giving me SSD:C as a move possibility so I assume it is therefore on D drive?
The game is running OK but it always only starts on the 2nd attempt.
The first attempt at startup gives me a desktop screen for 20 - 30 secs with nothing apparently happening – then this changes to a black screen for 20 - 30 secs - then this goes back to desktop and nothing happens.
So I then start MSFS again from the windows start menu and the game loads. I can spot the quick flash of a message and find behind the screen with MSFS running is a message box saying Game already running!! I assume that is a leftover from the first failed attempt. And I have tried the double click start and the Run as Administrator start - both give the same results.
Now my questions are:
Is the MSFS Uninstall feature a nice clean uninstall (without leaving files everywhere?)
At this stage , before all the multitude of settings are finalised, should I reinstall?