I realize that most problems I have had with toolbars are due to persistant browser cache.
The good old CTRL+F5 doesn't seem to be enough, so here are some other methods:
For general cache clearing, there is a common key combination: CTRL+SHIFT+DEL
Often you don't want to clear all cache, but just the cache for the pages you are working with.
For selective clearing cache - I was searching for it after upgrade to Internet Explorer 11 - read more here:
http://msdn.microsoft.com/en-us/library/ie/dn255004(v=vs.85).aspx
It was easier to find in IE10.
Chrome has an option in the settings (hit F12 for Developer Tools and look for the wheel in the lower right corner). Tick "Disable cache (while DevTools is open)".
In Firefox there are several add-ons (I haven't tested) and and it is possible to permanently disable cache with about:config network.http.use-cache = false. I haven't found the option in F12 Developer Tools in Firefox.