Well! That took some hacking!
I realized that I had not tried what you were describing but once I did... yes siree... BMP is the first choice.
OK, try this although it is like throwing the baby along with the bath water. Many formats become invisible but FIT is NOT one of them. ;-)
Launch PI, access menu:
Process | Modules | Manage Modules...
Find the one named BMP-pxm.dylib and double click on it and it becomes disabled.
Quit and relaunch PI. Voila. FIT is now first.
If you want to go back to the past, use Process | Modules | Install Modules
You may see nothing in the list although you know BMP is disabled. Make the module visible by pressing on the Search button below. Voila. You may now press Install and PI is back to its original state. Well almost. Because BMP is not module 1 any longer. If that is important... that I do not know.