Resaving a file I have opened for editing.

When I open a previously created document I receive a message stating it is and unknown user.
It asks me if I want to open a read-only copy or one that can be edited.
If I open an edit version I cannot resave it to the original file but have to change it with a slightly altered file name.

Could Avast be causing this with its anti ransomware?
And if it is - how do I solve the problem please?
I am using Windows 10 and Open Office 4.1.7

You don’t say what Avast version you have, so I have to presume (not good) it is Avast Premium Security as the anti-ransomware isn’t in the Avast Free version.

See attached image, an extract of the compare products at avast.com. That indicates the Anti-Ransomware protects files and folders against, deletion, modification, etc. in folders protected by the anti-ransomware.

As an avast free user I don’t have the anti-ransomware module, given what is in the attached image, presumably your Open Office folder is protected ?
Also, have you included the open office executable to the trusted apps list ?