Sorry, not finding anything about this issue, and I honestly don't know if the issue is Settings, or Upgrade &c. Here's the thing: Recent upgrade to Ubuntu 24.04. Snap version of Thunderbird (very problematic migration). It's working now, but because data was lost, and settings all re-set to zero with the Snap edition, there's been quite a bit of re-customizing &c. Here's the latest: Someone sends me an e-mail with a .docx attachment, a daily occurence. Try to open it with Libre Office, as I have been doing for twenty years, including Open Office. But Libre Office does not show up as a helper app. Can't be selected from the right click menu. Or .. . ? Maybe I'm missing something, some new way of doing the same old thing. When I go into settings and navigate down to Files and Attachments, I'm expecting a list of applications, and attendant actions. However, there's only a single line, for .pdf attachments. I don't see any button or facility enabling the user to add an application, and specify what happen when, for instance, you click on a .docx attachment. And yes, Libre Office *is* installed, I've been using it regularly.