D11263 already polished handling of the {nav Settings > Configure > Advanced > History} checkbox, i.e. unchecking that setting clears recent files, recent folders and the last used directory for copy/move/link.
Remaining issues:
[] 1. Even after unchecking the checkbox, {nav File > Open / Save As / …} still saves filenames to the `[KFileDialog Settings]` group. We can check whether this can be prevented, but otherwise it's not really an important issue, or at least not something which can be solved in Gwenview.
[] 2. {nav File > Open Recent > Clear List} clears the list, but the same list in the {nav Start Page > Recent Files} tab is only cleared after restarting Gwenview.
[] 3. The context menu for the {nav Recent Files} tab is broken, it should contain {nav Forget this File} and {nav Forget All Files} like in KDE4.
[] 4. For the {nav Recent Folders} context menu, the last action should be renamed to {nav Forget All Folders}.
[] 5. {nav File > Open Recent} should also make it possible to forget all folders, either by adding a separate action or by extending the behaviour of the (to be renamed) existing action.