You can configure Firefox so that it allows you to accept and reject cookies from websites as you browse the Web. Cookie-related settings are configured in the Firefox Preferences dialog box.
Before You Begin
77 About Cookies and Firefox
Open Firefox Preferences
From the Firefox window, select Edit, Preferences. The Preferences dialog box opens.
Select Privacy Settings
In the Preferences dialog box, select the Privacy icon to view the cookie settings. Select the Keep Cookies drop-down list. To have the option to deny or select cookies as you browse, select Ask Me Every Time.
If you don't want to allow any cookies, clear the Allow Sites to Set Cookies check box. But be advised that disallowing cookies can make many websites, more than you would imagine, act oddly and in many cases unsatisfactorily.
Open Website Exceptions
If you want to negate your cookie settings for a few exceptions, click the Exceptions button. The Exceptions dialog box opens.
Type a website URL in the Address of Web Site box and then select Block, Allow for Session, or Allow. These exceptions should be the antithesis of your main cookie settings (in the Preferences dialog), meaning that if you are blocking all cookies, some sites will be "allowed" to set cookies when you add them to the list and select Allow. After entering the exceptions, click OK.
You are returned to the Preferences dialog box. Click OK to save your preferences and return to the Firefox window.
Allow or Deny Cookies
You can now browse the Web using your new cookie settings. If you selected the Ask Me Every Time cookie option, a Confirm Setting Cookie dialog box opens when a website attempts to set a cookie. Select either Deny, Allow for Session, or Allow as needed.
If you choose to be asked every time, you may find that you are clicking the Deny or Allow buttons a lot because many sites seek to set multiple cookies. Again, only block cookies if you feel (or your system administrator feels) that cookies pose a threat related to your personal or business information.