Quick Answer
Cookies are enabled in Firefox by default. If sites keep logging you out, the culprit is almost always Enhanced Tracking Protection set to Strict or Custom, not a global cookie block. Open the menu in the top right, choose Settings, then Privacy and Security, and set Enhanced Tracking Protection to Standard. That single change keeps tracker blocking on while letting normal first party cookies work.
If you want to stay on Strict but unblock one site, scroll to Cookies and Site Data, click Manage Exceptions, type the site URL, and choose Allow. That preserves the rest of your privacy posture and only loosens the lock on the domain you trust.
Why Firefox sometimes acts like cookies are off
The most common reason a site forgets your login or empties your cart in Firefox is not a disabled cookie store. It is a tracker block. Firefox ships Enhanced Tracking Protection on by default, and the Strict tier blocks cross site tracking cookies, fingerprinters, cryptominers, and several script categories. Some shopping carts, single sign on flows, and embedded video players treat blocked third party cookies as a hard failure and behave as if cookies are off entirely.
Knowing which tier you are on matters. Standard blocks known trackers and cross site tracking cookies in private windows only. Strict applies the same blocks everywhere, which is what tends to break sites. Custom lets you pick exactly what to block, and it is where a misconfigured drop down can disable all cookies in one click.
The full path on desktop
This works the same on Windows, macOS, and Linux on Firefox 128 and newer.
- Click the three line application menu in the top right corner of the window.
- Choose Settings. A new tab opens with a left sidebar.
- Click Privacy and Security in the sidebar.
- Under Enhanced Tracking Protection, click the Standard radio button. This blocks trackers without blocking first party cookies.
- Scroll down to Cookies and Site Data and make sure Delete cookies and site data when Firefox is closed is unchecked, unless you really want to start fresh every session.
That order matters. Switching tiers first, then reviewing the cookie deletion toggle, prevents the situation where you fix the tracking tier but still lose your sessions every time you quit the browser.
Using Custom mode safely
If you choose Custom because you want fine grained control, the trap is the Cookies checkbox. Tick it, and a drop down appears with four options. Pick Cross site tracking cookies, or Cross site cookies including those from social media. Never pick All cookies in Custom mode. That option blocks first party cookies as well and will break virtually every logged in service you use, including banking, email, and dashboards. The other two custom options, Cookies from unvisited websites and All third party cookies, are tighter than Standard but usually still let normal sites work.
Adding a per site exception
Sometimes you want Strict everywhere, except for your bank, your work portal, or a forum you trust. Firefox supports this through Manage Exceptions in the same Privacy and Security panel.
- Scroll to Cookies and Site Data and click Manage Exceptions.
- Paste the full site URL, including https, into the address field.
- Click Allow, then Save Changes.
The exception applies to that exact origin. If your bank uses a separate login subdomain, add both. The list also accepts Block and Allow for Session entries, which is useful for a site you want to use today but not retain after you close the window.
On Firefox for Android
Tap the three dot menu in the bottom right, choose Settings, then Enhanced Tracking Protection. Set the tier to Standard if a mobile site keeps logging you out. The Android app also exposes a separate Delete browsing data on quit menu, which is the mobile equivalent of the desktop session deletion toggle. If you only want to clear data for one site, long press its history entry, choose Delete from history, and Firefox removes its cookies and storage immediately.
Troubleshooting when nothing helps
If you are on Standard and a specific site still cannot save a session, the issue is usually an installed extension rather than the browser itself. Disable ad blockers and privacy extensions one at a time and reload. uBlock Origin, Privacy Badger, and AdGuard all have their own cookie and tracker rules that sit on top of Firefox. A clean test in a private window with extensions disabled, available under the menu as New private window, isolates the problem in under a minute.
One last check. If a site refuses to load at all, look at the small shield icon to the left of the address bar. Click it, then toggle Enhanced Tracking Protection off for that site. The page reloads with no tracker blocking, and the shield turns purple so you remember you made an exception.
The takeaway
Cookies in Firefox are not a single on or off switch. Standard tracking protection plus a short exceptions list is the configuration most people want. It keeps the marketing graph from following you across sites, lets shopping carts and bank logins work, and gives you a clean per site override when something stubborn breaks.
