When not able to double click to minimize window..

I have / had the problem of not being able to minimize windows with double clicking window. After trying a different Mighty Mouse then Magic Mouse still had the same problem. Trashed mouse prefs. No difference. Restart iMac - same. Then tried turning it off & unplugged to reset. I was able to minimize for a short tine. Check Mouse setting in system prefs. Made changes to no avail. To solve the problem the culprit was in disability prefs. The Mouse double click was set to fastest setting. Slowing the setting fixed the problem. Oddly doing thAt in Mouse setting did not. Hope that may help others that may have the same problem. This was on my 2011 iMac - El Capitan.