Advice Request Firefox Temporary Containers - How to set cookies?

[HarborFront]

I have an issue especially with sign-in sites

Take example MalwareTips forums. If I sign in and later I close my browser Temporary Containers will delete its cookies. When I open the next time I need to sign in again. Very troublesome here. Temporary Containers allow cookies for the site to be saved but there's no instruction of how to save the cookies. See attached.

Can somebody advise what to fill in those blank spaces in order to save a cookie?

Thanks

 

[SeriousHoax]

I have a problem with FF Multi-Account Containers

Before formatting my Laptop

Using FF I exported the bookmarks as html file

Here by bookmarks of FF-Account Containers do you mean the containers? The sites you chose to always open in containers? In that case those are not really bookmarks. FF Multi-Account Containers has a separate file in the Firefox profile folder named "containers.json" where this containers are stored.
The best to way to backup your data is to backup the whole profile folder before windows re-installation.
Copy "C:\Users\xxxx\AppData\Roaming\Mozilla\Firefox\Profiles\xxxxx.default-release" this folder somewhere else. Then after re-installing windows, install Firefox and open it once and then close. Now copy all the contents inside your backup folder into the new profile folder and choose to replace all. Now Open Firefox again and everything will be the same as before including websites log in and everything.