FireFox Cache Clearing
1. Click the menu button and choose Options.
2. Select the Privacy & Security panel.
3. In the Cookies and Site Data section, click Clear Data….
4. Remove the check mark in front of Cookies and Site Data.
5. With Cached Web Content check marked, click the Clear button.
Tip: Here's another way to clear the Firefox cache:
Click the Library button , click History and click Clear Recent History…. Next to Time range to clear, choose Everything from the drop-down menu, select Cache in the items list, make sure other items you want to keep are not selected and then click the Clear Now button.