conflict between windows

Hi. I work with a number of windows sized so that they can all fit on my desktop. I use Word docs, XL sheets and a user form, Outlook and another piece of bespoke software which uses word for editing. I am finding that often when I move between applications there is a frustrating scene as the apps battle and create a flicker whch can only be stopped by holding down the xl spreadsheet (this has no macros, by the way so screen updating is not the issue here). Is there something I can do to stop this? This affects all my colleagues as well.