he usual method is:

(1) Change the default cookie lifetime from "however long the website wants" to "current session only"

(2) Create exceptions on a site-by-site basis as needed

(3) Do not use any other method of clearing cookies, since the current session only cookies will be culled automatically

For #1:

Windows: "3-bar" menu button (or Tools menu) > Options Mac: "3-bar" menu button (or Firefox menu) > Preferences Linux: "3-bar" menu button (or Edit menu) > Preferences Any system: type or paste about:preferences into the address bar and press Enter/Return to load it In the left column, click Privacy & Security. On the right side, set "Firefox will: Use custom settings for history" and then:

[X] Accept cookies from websites Accept third-party cookies: Always Keep until: I close Firefox [_] Clear history when Firefox closes

For #2:

You can use the Exceptions button on the Options page, but the formatting can be particular. It may be easier to use the Permissions panel of the Page Info dialog while you're on the site that should be allowed to set cookies. You can call that up using either:

right-click a blank area of the page and choose View Page Info > Permissions (menu bar) Tools menu > Page Info > Permissions Scroll down to "Set Cookies" and uncheck the "Use default" box, and then select the permission you prefer (in this case, "Allow").

Changes are saved as you go, so you can close this dialog when you're finished.

For #3:

Make sure "Clear history when Firefox closes" is not checked. Or, if you want to clear cache or other data, click the Settings button to the right and make sure that neither Cookies nor Site Preferences is checked.

Cookies: does not obey exceptions, removes everything Site Preferences: these are your exceptions, don't remove them Does that work for you?

Is there a simple way to avoid all cookies and finally have some privacy? The Firefox instructions on this are so complicated and long, that one does not know how to avoid ALL cookies.

Do you mean on your Mac or on an iOS device (iPhone/iPad)?

On your Mac, you can set Firefox not to accept or return ANY cookies, but some sites will not work correctly. One reason some sites need to use cookies is to connect your requests to a single session. But if you aren't logging in or submitting forms or shopping, then you may not need your requests to be connected.

To experiment with different cookie settings go to the Preferences page, Privacy & Security panel, and switch to "Custom" Tracking Protection. Then you can test different options for blocking. If you choose one of the first four options, you also can combine that option with the suggestions in the earlier reply from fardeenbhuiyan: