XnView Software

When saving an image to another format you can pop up the option dialog.

The check-boxes for the metadata should reflect the codec's abilities:

If one of the metadata cant be changed, it should be grayed.
If one of the metadata doesn't exist, it should be unselected.

Actually it is very confusing and inconsistent.
Mostly all metadata are grey and selected,
although in the dialog afterwards it says none of it can.
Sometimes (for png for examples) all can be changed,
but when doing the saving it says "Just a joke ...".
Not nice.

which checkboxes?

It's about all "Keep"-checkboxes.

They are selected, although the format doesn't support it.

They are grayed (and selected), although ...

When saving it says: "April's fool, I can't do something of that ...".

Just do it logical. Offer (per every format) the abilities that the format supports.

which format for example?