Help me fix this annoying RPI4 Buster printing problem

[Bruce Labitt]

At the moment I'm on an RPi4 running Raspberry Pi OS.  My laptop died 
recently.  I'm trying to figure out this OS works.  Have to say, it's 
been painful in many ways.  One is that the RPI is slow...  It will be a 
little while before I get a replacement laptop, so I have to deal with this.

Although I have configured a network printer (running on CUPS server on 
an RPi2) some apps on my RPI4, like, GIMP, gpaint, and LibreOffice seem 
to retain former and incorrect printers.

My GoogleFu seems to be terrible.  Can't seem to find a way to purge 
these old settings from showing up.  There has to be a way to do this!

I've found this experience to be pretty darned exasperating.  I find 
lots of apps, including gpaint, don't just work on RPI4 Buster.  Doing a 
print, or a print preview from gpaint should NOT cause the app to fail 
and terminate.  Especially if the network printer actually is configured 
correctly.  I can print a test page just fine.

Where are system wide print settings managed?  File names and 
directories?  Does gpaint have a shadow set of printer settings? Where 
are they stored?