Steps to Clear Cache and Cookies in Mozilla Firefox Web Browser

1. Click the menu button (3 lines in the upper right-hand corner) and select Settings.
2. Select the Privacy & Security panel.
3. In the Cookies and Site Data section, select the Clear Data button.
4. Remove the check mark in front of Cookies and Site Data.
5. Keep the Cached Web Content checked. Select the Clear button.
6. Close the Firefox web browser. Any changes you've made will automatically be saved.

Mozilla Support to Clear Cache and Cookies