I just double-checked and this setting is retained between sessions for me. Are you perhaps clicking on any other search collection tabs between searches? Those will reset the search tool to the settings that were saved into the collection initially (to make modifying it easier). Now, at that point if you click right back on the Search Results tab, it should go back to draft-only, but if instead of doing that you go straight to a new search off of the search collection tab, it will modify the current search settings, set by that tab, and thus if that tab did not have draft-only set, your main Search Results tab will go back to it being off. I think that is the only condition where it should be losing the setting, so let me know what else you are doing, if not.
No, for me. I can select “Search Manuscript Only,” exit the app, start it up again, and it is unselected. I can also select it, search for something, exit, restart, and it is unselected.
So there’s no confusion, this is the option I’m talking about: