Searches normally work this way, and it is the intended behavior of our search forms. What you are wanting is for the user to be able to select only ONE search term? If so, that can only be done with custom javascript, which, when one field/term is clicked, deselects any selections in the other fields.

Sorry, but I do not have an example I can give you, as I don’t think anyone has asked for this before.

You would need to employ a coder to do this for you.

If you could forgo the single reset button (and have either no reset button or one per field), you could set this up as a separate form for each field, and one form with all the fields – just to use that as the results shortcode.

That would do as you want. I am not sure if Ajax would work with that though.