How to permanently delete a read only protection

It often happens that I open a .doc or .docs file and find it protected (read only). Examining the various possibilities I found that the protection is not applied to the file, but to the sections in which the file is split. Each time I had to remove the protection of the sections, and even the sections themselves, so I was able to edit. Then I saved the file and closed Libre. However, when I reopened the file it was again split into protected sections. Why? Furthermore, if I send the file to others, they cannot edit it because it is protected again. The only solution I have found is to select all the text and copy and paste to a new document. This way the sections don’t reappear, but I lose any images and text boxes. I use windows 10 home and Libre 7.1.6. Any solution? Thanks

Does it still occur if you save it as .odt?

Are you trying to open such files by double clicking attachments to emails?