Newbie finds KATE acting strangely

[Richard Owlett]

My system running Debian 9.13 with MATE Desktop Environment 1.16.2
KATE's Help menu reports
Help->About Editor Component
Kate Part
Version 5.28.0

Help->About Kate
Kate
Version 16.08.3

I'm relatively new to KATE.
I've used many editors {even had an intro to TECO back in 70's)
My current primary editor is Pluma 1.16.1 .

I've been experimenting with KATE for several months doing stuff that 
could easily have been done with Pluma. No problems and no surprises.

Today I started exploring regular expressions.
Started KATE and exited some straight text and a list of 1 and 2 digit 
numbers. Searches went well until attempted to use regular expressions.
No luck until I clicked on Search and Replace in lower left of screen.
There was a box allowing me to select a mode. then I had some  luck. 
then things went strange.
Could not get back to environment I had had.
Exited KATE and did a couple power off on cycles.
KATE is apparently "remembering" things across exit/reload cycles and 
even power off/on cycles.

*QUESTION*
How do I start KATE as it would have been if it had never been run on 
this machine?

Help please.
TIA

Documentation I have the following bookmarked in my browser:
https://docs.kde.org/stable5/en/kate/kate/index.html

https://docs.kde.org/stable5/en/kate/kate/introduction.html

https://docs.kde.org/stable5/en/kate/kate/fundamentals.html

https://docs.kde.org/stable5/en/kate/katepart/

https://docs.kde.org/stable5/en/kate/katepart/regular-expressions.html