I do not understand the hamburger reference as, on a Mac I do not see this. I only have one account. I think that the problem arose when I deleted my one account and set it up as IMAP. However, because I am a TalkTalk customer I am using the mail.onetel.com as incoming and do use SMTP.onetel.com as outgoing and I cannot link everything with my iPhone unless I use a POP3 account on my Mac desktop. So, I converted it back to POP3 and now I have an inbox, which if I have it highlighted and click on get messages nothing happens, whereas if I highlight the named account within the Inbox drop down and click on get messages it looks for messages.

So, my problem is that I just want the inbox to work when it is highlighted and I click on "Get Messages", and I need to not have both "inbox" and "named account" showing all the messages..

Yes, and this is the issue. If I click on get all messages it only works if the named account is highlighted rather than Inbox being highlighted.

Here's a screenshot:

I can only click on "Get Messages" when the named account is highlighted and not on "Inbox". In the past I only had Inbox and highlighted that and clicked on "Get Messages" .

Non of this is going to help in the problem that I have though.

I have posted a screenshot of the issue and I need to find a way to have the Inbox as the place that I highlight and can click on to "Get Messages" as it does not do this now and I have to highlight the named folder to get messages. There is a duplication in the mix.

I notice now also that the Sent folder has a sub folder with my name on it which I have to open to see my Sent messages. This is all very different to how I have used Thunderbird for 15 years and never had this problem before.

Have sorted this now thanks with some tweaking and repairing of folders of main account folder.