How are you clearing cookies? '''Method #1:''' Turn on [X] Delete cookies and site data when Firefox is closed This setting allows exceptions -- you'll see the list if you click the Manage Permissions box to the right.* '''Method #2:''' With History set to "Firefox will: Use custom settings for history", turn on [X] Clear history when Firefox closes, and in the Settings dialog, tick the Cookies box This setting disregards exceptions and flushes all cookies. Make sure you do not clear Site Preferences because that will flush your actual exception settings. ---- ''* There is a very particular format for cookie exceptions, so to set one up, I suggest this method:'' While you are on Ecosia's site, call up the Page Info dialog using either: * Ctrl+i (for Mac, Command+i) * right-click a blank area of the page > View Page Info * (menu bar) Tools > Page Info When the dialog comes up, click the Permission icon at the top to show that panel. Scroll down to "Set Cookies" and uncheck the "Use default" box, and then select '''Allow''' to let the site set persistent cookies. Then you can close this dialog.