TT for Windows 2021 restarts after closing

I'm just starting my 2021 return using TT Premier for Windows, entering random bits of info as they come in.

 

When  I close a session by clicking the red X in the window title bar, TT closes, then reopens a few seconds later. This only happens if I have made some change to the data and told TT to save it after clicking the X. I would prefer it stay closed when I close it.

 

TT 2021.47.15.72

Version 021...000...0415 (not a phone number)

[I never understood TT version numbers]