Adobe’s Flash player is known to store cookies on your computer, independent of your web browser settings. So, if you have Firefox deleting all the cookies after your session, you may still have additional tracking cookies on your computer via Flash.
In some cases, these cookies can be good depending on the website. For instance, setting the volume of the Flash plugin for a particular website. Other cases, they could be used for targeted advertising.
To check your Adobe Flash Cookies:
You can check what cookies are on your Adobe Flash player through the Settings Manager. The Website Privacy Settings panel will show a list of sites that are storing information on your computer.
- Select Website Storage Settings Panel
- Click on “Delete all sites” button to clear all Flash cookies.