the importexport addon is still alive and well. just click the addons option from hamburger menu or tools>addons from menu bar - and then enter the word import into search box and it pops right up. This may not work if you are using beta version,

But I need to export from the old computer. There is only one big export button which seems to want to export everything. If I remember I could export each folder independently in the past.

What is it that you want to do? The importexport addon also exports.

I highlight the folder, click tools>export and I get a big export button that I didn't dare click because it seemed to indicate that everything including my profile would be exported. There are about a 1000 messages in the folder and in the other 6 folders I want to save. I don't want to export it all in one big giant file. I wanted to export each folder separately then import them into a folder on the new computer with the same name. I know I did that in the past. I've been using Thunderbird for a long time.

You're confusing me. Do you want to move everything to new PC, or just certain folders? Please be specific and I can then advise what to do.

I just want to copy certain folders from one computer to the other. Both have Thunderbird.

assuming Windows, on old PC, - click help>troubleshootinginformation in thunderbird - scroll down to 'profile folder' and click 'open profile' - exit thunderbird - assuming the desired folders are in either a POP account or Local Folders , copy the Mail folder to external media - on new PC, create new Local Folders folders - highlight a new folder, rightclick and select the importexport options to import mbox - click one of the desired folders on the external media (IGNORE the .msf files) and click ok. - repeat for each folder

Thank you. I will give it a try. I will keep this open until I get it to work.