Type '''about:preferences#privacy'''<enter> in the address bar. The button next to '''History, ''' select '''Use Custom Settings. ''' Under History, turn on '''Accept cookies from sites''' and '''Accept third-party cookies. ''' At the far right, press the '''Exceptions''' button. Place those websites you don't want here. Warning: Blocking 3rd party cookies may cause issues. https://support.mozilla.org/en-US/kb/websites-say-cookies-are-blocked-unblock-them

You can check the Cookies and Enhanced Tracking Protection settings in "Options/Preferences -> Privacy & Security". *https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop