TB’s default threading can be frustrating, especially with long conversations. One trick I use is to temporarily disable threading for accounts where chronological order matters. Regarding PDFs and docs, I’ve had better luck opening them externally rather than relying on the built-in preview.

You can turn off global threading in settings.

You can turn off global threading in settings.

OK, i know. But what this is default on??

Regarding PDFs and docs, I’ve had better luck opening them externally rather than relying on the built-in preview.

Right. That's how I set it up. LibreOffice, Adobe Reader. But after a TB update, it can lose these settings. I manage fine, but less technical users get confused when attachments suddenly stop opening correctly.

Rick said

You can turn off global threading in settings.

OK, i know. But what this is default on??

If you mean why is this the default, it's because most users expect it.

It should not change on updates.

TB can also lose attachment opening preferences in programs after an update, such as .pdf or .doc. Note that some PDF documents don't display correctly in the built-in preview and require the use of Adobe Reader.

Best to post different issues in different questions.