In theory: F5 let me change bar settings
- i.e. it lets me change main key temporarily from major to minor

Key change has no effect in Roman Number analysis.
Major-->Minor
Minor-->Major

Current settings:
[KEY]
Select Eb (example)

[DISPLAY OPTIONS - uncheck this]
[ ] For Roman Numerals Of Chords in minor keys, use relative major

What I am trying to do is learning songs by heart by making a simple harmony stories using Roman Number system in my head. If I can explain the song harmony this way I can play it in any key.

[My thinking goes like this]
1) This is AABA form song
2) It goes in major key in A1 & A2 sections this way ...
3) But in B section it goes to relative minor this way ...
4) it comes back to major key in A3 section this way ...

At the moment BIAB is unable to react to the internal key change, when
Roman Number notation is used.