Usually, for packing I use .zip format. That's simple:
- I check the files,
- press Alt_F5,
- Enter
and... that's all.

Sometimes, very seldom, I need to use another format (very often: just .lst). And that's also very simple:
- check the files,
- Alt_F5,
- change the format,
- Enter
and... that's all.

As I use packing function very often, I of course almost don't look at the screen.
But next time... when I again want to pack my files (to my typical .zip format)... I've got a problem. Very often I just forget to change again the format and instead of .zip archive file I've got for example .lst file

My suggestion: It would be good to :
or - add a button to the packing form (after pressing Alt_F5) - "Make the format default" and then even if the format was changed once, the next time the default one would be chosen.
either - add a parametr to packer options - "Default format".