XnView Software

Q: When does XnViewMP save changed metadata (how do I make it save metadata)?
Detail: I want to use browser to apply/remove keywords (metadata) (by un/checking the boxes in "Info" window with "Categories" selected. Then save the changes (with no changes to the image data (non-metadata)). How please?
Thanks!

When you change the selected file

Thank you, Pierre! Your prompt drove me to find what was happening.

One needs to deselect the changed file:
XnViewMP saves Category (keyword) changes when the (changed) file(s) is deselected (including when the selection moves to another file(s)).
NOTE: If one quits XnViewMP *without* deselecting the file then no changes will be saved. THIS CAN APPEAR AS INSTABILITY TO THE USER. (This is what was happening to me.)