How do I fix the “sorry, you are not allowed to access this page” error I get on the “plugins > settings” links?

I discover this message “Sorry, you are not allowed to access this page” mostly occur when various WordPress sites are in the same phpMyAdmin – all bearing the same table prefix, irrespective of the database name. I can’t tell how many WordPress sites are expected to be in the same phpMyAdmin with the same table prefix.