I don't think there is a tutorial for WLM vs Tbird, and I don't envisage anyone creating such. Be free to Google-search for one though, you just might find one. What exactly do you mean by "losing Inbox saved emails"? Explain your normal workflow (in Thunderbird) that somehow results in loss of emails. Also, what type of account is it (IMAP or POP), and what are the current account settings as far as deletion of messages is concerned? Include screenshots if you wish.

Lost emails. Win Live Mail used to save Inbox emails here on my computer. I just lost a bunch of Inbox T-Bird emails when they were wiped from my ISP's email server. How can I permanently save Inbox emails in T-Bird, on my computer here? Thanks. Very frustrating problem with all those lost emails.

Sounds like you configured your account to use IMAP instead of POP. What you need to do is remove the account and add it as a POP account to Tbird. See https://support.mozilla.org/en-US/kb/faq-changing-imap-pop for details. You should also get familiar with https://support.mozilla.org/en-US/kb/difference-between-imap-and-pop3

Ah, thanks, it does sound like the lost emails in the Inbox is because of the difference between IMAP and POP. If I create a Local Folder called "saved emails", and move the emails from the Inbox to it, that I want to save permanently, will that Local Folder be immune from changes at the host's server? In other words, are the emails in the Local Folder really in there, and not just mirrored from the host server? Thanks again.

Yes, that's exactly what a local folder in Tbird is for. Its contents are unaffected by server activities.

Ah, thanks a lot. That solves the problem. This is the sort of thing, concerning differences between T-Bird and other programs that many of us have been using, that would be very useful in a how-to when switching to T-bird. Based on the history of questions in here, the problem we encountered has been seen by many before us.

Instead of specific-program vs Tbird usage tutorials, you could instead take advantage of the many Tbird knowledgebase articles available here https://support.mozilla.org/en-US/products/thunderbird or via the (F1) Help menu in Thunderbird. It helps when migrating to a new program to explore the available help resources instead of going in blind.

Also note that Thunderbird is NOT an IMAP-only client. It also supports POP, which is the same protocol you used with WLM.