Edit: Rewritten from scratch on Wednesday, June 16, 2021: I am running the new Firefox 89.0 on Linux. Under the Edit menu, the Preferences option is now called Settings. Please open Settings and search for '''site data'''. This displays the pertinent settings for '''Cookies and Site Data''', and for '''History'''. A Web SDR site is a website that gives each of its visitors the ability to tune a Software Defined Radio chip to a different frequency, independent of other users' listening preferences. The audio is streamed back to the user. It requests that the user supply a user name, often a ham radio operator's callsign. This is used to display on the radio dial where each user is listening. If a name is missing, the user's IP address is used. A cookie is stored with the user name, and if that cookie survives to the next visit to the site, the name does not have to be re-entered. The web SDR can allow users to save custom memory presets, and cookies are said to be used to save memory presets "on ''your'' computer," and not on the server. '''I had set cookie preferences for each site to always allow cookies, and my username was indeed carried over from one browser session to another. But my presets were never saved.''' I finally discovered that it was not a cookie, but offline site data storage on my computer that retains these presets. Under the '''History''' section in Preferences of earlier versions of Firefox, I told Firefox to use custom settings, and then I had set first- and third-party cookies to be allowed for the session. I told Firefox to Clear history when it closes, and in the "Settings ..." dialog, I unchecked everything but cache and offline site data. Only cache and offline site data were deleted. The '''History''' section in Settings in FF 89.0 is still set for Firefox to use custom settings, but cookie options are not listed. I still tell Firefox to Clear history when it closes, and the "Settings ..." dialog is the same. In the '''Cookies and Site Data''' section in Settings, I tell Firefox to Delete cookies and site data when it is closed. In the "Exceptions ..." dialog, I enter the address of the website and hit "Always" for everything entered, to save the site's cookies and data from the bulldozer. It occurred to me that there are two duplicate means to clear cookies and site data. I went to '''History''' and opened the "Settings ... " dialog again and cleared the checkbox for offline site data. NOW my stored memories on the Web SDR sites are still here! In Firefox 89, do not use '''History's''' Clear history when Firefox closes to delete cookies or site data, for that will blow away the cookies that were saved in the '''Cookies and Site Data's''' Exceptions! The browser was overhauled, and '''History's''' handling of cookies and site data became obsolete. I do have a question here: If I am on a site, I can click on the lock in the address bar to retrieve a series of screens that lead me to the Security tab, and to its left, the Permissions tab. By selecting the Permissions tab, I can set the site's permissions for cookies and for persistent storage of site data. If I set to allow cookies and allow site data in Permissions, does that enter the site address into the Settings' '''Cookies and Site Data's''' Exceptions dialog? Or must I still copy the address of the site and go to Settings and enter that in Exceptions also?