XnView Software

you can disable 'Use multiple CPU cores' or change 'If an output file already exists'
Oh, so that's what 'ask mode' meant!

Thanks for the quick reply. I'm grateful for the help, and for this handy tool.

For future reference, is there documentation I could consult? I'd just as soon not bother ...

I installed XnView on someone's strong recommendation, and I like its features. But I have one problem: every time I go to quickly use it, dragging in a few webp files usually, I get a popup error when I hit convert: "The 'Use multiple CPU Cores' setting was disabled. This setting can't be combined ...