You can turn it off in the "add on management" section. I can't remember the add-on and module you need to disable, but it's there somewhere (check with your users too - when I did it, there was a lot of negative feedback and it was quickly re-enabled)
Just a warning - disabling the preview feature for attachments (as described here - https://community.atlassian.com/t5/Confluence-questions/Is-there-a-way-to-turn-off-the-quot-preview-quot-feature-and/qaq-p/201649) has pros and cons:
There's an open feature request in the Confluence backlog to allow disabling of file previews for specific file types - CONFSERVER-36899. It is still open as of today :-(
More and more people are building their careers with Atlassian, and we want you to be at the front of this wave! Important Dates Start the Certification Prep Course by 2 April 2019 Take your e...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs