Move them to Local Folders.

So the business account folders I set up under each inbox need to be recreated in Local Folders and then move all of the messages to their respective folders?

'Fraid so.

Your messages are in one place and you want them somewhere else. So you have to move them.

Some users seem to get away with just dragging the folders into Local Folders. I wouldn't risk it myself. Email isn't good at sustained transfers of huge amounts of data, and here you'd be asking it to download all the folders and all their data in one action.

You could try it a folder at a time. But be wary of nested folder structures. And to work with nested folders you'll need to create the empty target folders by hand to avoid the deep copying that would otherwise ensue.

Another reason I advocate copying messages (not folders) is that drag and drop can be a little bit hit and miss. It's more reliable if you do a multiselection then right-click and use Move to... - but this operates on messages only and not on folders.

So could I have avoided this by setting up the accounts as POP instead of IMAP?

I just tried a trial message and it is still on the server. Although it doesn't show up in the inbox, there are four visible messages BUT in the parentheses next to Inbox is the number 5. Same thing with sent folder. I moved a sent message to Local Folders and the number beside Sent is one greater that the messages that appear on screen. Can I just switch everything to POP and eliminate this issue?

Quite possibly. POP wouldn't suit me, but I'm using my email accounts on several different devices at several different locations. For an account used only in one location, such as the office, POP might work well.

If I switch to POP will I lose the messages already in Thunderbird?

If you "switch to" POP then yes.

Instead, set up the account again, but using POP and alongside the existing IMAP-connected account. Then you can set about moving messages from the IMAP-connected account into the POP-connected account. When that's done you have no further use for the IMAP-based account in Thunderbird and you can delete it.

I am trying to head you away from a common mistake which is twiddling with the settings in an attempt to convert the account in Thunderbird from IMAP to POP.

POP and IMAP are two separate protocols and in my experience use two different client modules in an email client. If you have IMAP you need the IMAP client module. Telling it that it is connected to a POP server cannot intrinsically change its behaviour.

Are you using Unified Folders view? One reason I do not use that is that it cannot count.

Thanks for your input. I should have just set up the accounts as POP3. For some reason I thought that there was added security in IMAP, but now I don't believe that to be true. I tried creating duplicate POP3 account but once it was set up I couldn't utilize Account Settings. Every time I opened it I was told there was already another account with that name. The one thing in retrospect that I didn't try was closing TBird and re-opening after removing the POP3 account. I have done the work to accomplish my objective in IMAP but I can't imagine ever using it again. Live and learn. Die and forget it all.