Using And/Or Expressions in Search Criteria

If I check the Use Expressions box to use parenthetical expressions in summary search criteria, I am able to proceed as expected, defining parenthetical criteria expressions which have the anticipated effect.

If I then edit the summary search criteria again, the Use Expressions box is unchecked. However, if I check the Use Expressions box again, my previously defined parenthetical summary criteria expressions are still there. Furthermore, whether I just leave the Use Expressions box unchecked as it is when I edit the previously defined search, or even if I explicitly check the Use Expressions box again and then uncheck it, the previously defined parenthetical summary criteria expressions continue to affect the search results. It appears the Use Expressions box does not affect whether defined parenthetical summary criteria expressions  are used, only