The Firefox cache temporarily
stores images, scripts, and other parts of websites while you are
browsing. This article describes how to clear the cache.
Clear the cache
Clear Cache from the recent history
At the top right of the Firefox window, click on the Firefox button and then select Options (3-line) icon
Select the History panel.
Click on Clear Recent History...
4. Clear
Recent History window will pop up.
Select the checkbox beside the Temporary cached files and pages or other temporary data from the list.
Select Everything in the When field to clear all history for all time (this is recommended).
Click Clear at the bottom of the popup menu.