Hi,
the four vertical checkboxes at the bottom are unrelated to saving - they control different options.
The four horizontal checkboxes correspond to the four save options in dropdown on the save button on the left of the live stacking area. These save options are already documented in detail here -
https://docs.sharpcap.co.uk/4.1/#Actions%20Group
I will investigate the missing 32-bit save file - I am seeing the same thing here, which is not expected. I suspect the fact that no-one has reported this before tells us that most people save the 16 bit option!
cheers,
Robin