When above is enable, additional permissions will be added in the Profile:
- Edit My Own Post (enable by default for standard profile)
- Edit Posts on Records I Own
* this include ability to edit Post in Chatter group where user is the Manager or Owner group
Both permission is not enable by default for custom profile, as admin you need to enable them in Profile or Permission Set if needed.
Administrator and Users with the Modify All Data permission can always edit all Posts.
Chatter Free, Chatter External and Customer Portal users do not have this permission.
But, this edit capability only for Post, not for Link, File or others.