What you describe is normal and has always been the case. A thread is a conversation and starts with the initial email (which can be sorted in either acsending or descending order) followed by responses in the order received. Hence newest at bottom of thread. If threading is enabled, the sort order of ascending and descending is to do with the initial email in conversation and not its thread of conversation.

Some workaround options that may help: right click on email and choose 'Open message in conversation'. this opens a new tab with all emails both sent and received in that conversation. Uncheck the threading and then sort by Date to put newest on top. or: If you need to quickly see only the unread threads, instead of scrolling, I use the Quick Filter Bar option 'Show only unread messages' icon - looks like a pair of sunglasses. This removes the 'clutter' of the 'read' threads. Click on same icon again to revert to normal view. or there is an addon called 'Thunderbird Conversations', but I've not tested it on latest TB version. https://addons.mozilla.org/en-US/thunderbird/addon/gmail-conversation-view/ If you click on a collapsed threaded conversation, it makes the newest message immediately visible in the Message Pane (although, technically, it's still on the bottom.)

Another option: See if this is what you are looking for:

click on far right column header icon to see drop down options. Enable the 'Order Received' column header. see image below as guide.

then sort by 'Order received' instead of 'Date' with Descending and threaded.

Thanks Toad-Hall.

I could have sworn i had this the way i wanted it before - but maybe not. Its really frustrating that Thunderbird doesn't order things the way i want. Outlook (work emails) conversation function does it this way round where the newest email will be at the top of the conversation rather than the bottom. Don't understand why Thunderbird wants it the other way around.

Anyway - thanks for the reply and offering your help.