How can I prevent deletion AND modification of main thread posts?

[bluedagger]

I know I can make users not be able to delete their threads, but it's happening many modify their threads with gibberish in order to "erase their tracks" i guess.

How can I prevent that? Only for thread posts.

[Ikerepc]

You can do that for each group in ACP -> Users & Groups -> Edit User Group -> Forums and Posts

Here you can choose if users can edit their posts and for how long after posting