Frequently asking for password

Hi

The past few days I have frequently been getting a pop up window telling me to sign in to Acrobat DC eventhough I am signin in my account.I noticed that this is happening when I am opening a pdf document from e mail or some attachement receiveing from others (like bank statements).

If I am opening the files from the sysyem ,it is opening without any problem.

Can you update me that if any settings got changed or any update is required for the account ?