How to clear the cache in Firefox browser on Windows
Latest Versions of Firefox
Close all open Firefox windows and tabs. Open a new Firefox window.
Click the Menu button in the top right
Select the "Options" button (Marked by a gear icon) - On Mac the button will say "Preferences" like below
On the left select the Privacy & Security tab
Click "clear your recent history"
A dialogue box will appear, select the items to delete - make sure that "Cache" is selected - and verify that the time range to clear is set to "Everything"