Hi Erik,
It sounds like you may be referring to the functionality to edit office documents in Confluence (please let me know if I misunderstood).
Confluence 6.11 introduced the Companion App to edit files, which replaces the old "Edit in office functionality" (See Confluence 6.11 Release Notes). Once you have the companion app installed, you should be able to edit files by clicking the file to open a preview, then clicking the Edit with dropdown menu. Alternatively, you can click Edit next to the file on the attachments page.
For full steps, see the Edit Files documentation.
I hope this helps!
– Zak
Please also note that this functionality with the Atlassian Companion App (which I love) is more or less broken with the new editing experience (Fabric Editor) for Confluence Cloud. Hopefully this will be fixed soon.