In fact, a LibreOffice feature is the creation of thumbnails, so you could see a "preview" of the contents instead of the Writer icon in file manager. Check for yourself by changing the extension of (a copy of) one LO document to
.zip and open the
I don't know if it is possible to disable this feature.
Looking around in Ask.Libreoffice, I found the following:
- Rename your file to
.zip file and, from within
peazip or whatever you are using.
- Navigate to the folder
META-INF and open
gedit or equivalent plain text editor`.
Delete the line
<manifest:file-entry manifest:full-path="Thumbnails/thumbnail.png" manifest:media-type="image/png">
Back in the main folder of the zip file, delete the folder
- Close and rename back to the original ODF extension.
Note: This is valid for LibreOffice files, irrespective of the OS.
As for the OP's question, is a matter of either disabling the thumbnail preview as suggested in comments or deleting the thumbnail and setting a password so the contents of the file cannot be seen by anybody, depending on what the real needs or desires are.