Here's the thing "password manager" does just what it says manage login only. It doesn't open attachments that is coming from the email services or online services your using that is showing that. I think your getting attachments in email or online services confused with password manager that saves login and enter them on the remember password sites during logins.

Mark, Thanks for your reply. Am using Dashlane for years as an extension on my Firefox Browser as my password manager.

One of its facilities is Secure Notes where data can be stored directly and/or as attachments. I have been able to access these secure files in the past.

Now, while Dashlane still works as my password manager and I can access the directly-entered data in the Secure Notes, I cannot access the attachments.

I reported problem to Dashlane Support. The solution arrived at was to use another browser.

I now have Dashlane working fully as an extension in another browser and can open my attachments.

But, I would like to continue using Firefox. Can you help? Chris.

Where do I go for further support from Firefox?

This sounds more like a Dashlane support request then a Firefox as if your not using Firefox password manager then that's a Dashlane support request. Firefox doesn't open attachment that is based on what the site uses to open it's attachment. Attachment usually refers to email services opening or downloading attachments by default Firefox can't open attachment it uses other software to do that feature. That's what I understand in opening attachments.