Security in Contributions

I've been asked by an organization in our consortium to restricted access in Contributions for a couple of security groups and I'm not able to find a way to restrict what they would like to restrict.  Am I just completely missing it?

I need to disable the Adjust and Write-Off buttons on the Contribution Entry screen for one security group in the organization. I haven't been able to find how or where to do that. Nothing in the security module is jumping out at me and I'm not finding anything in the help system.

Also, is there a way to make it where a security group is unable to modify a payment schedule but can still change the CC attached to the schedule. This is the other request, but I'm not able to find a way to do this either. I'm really hoping I'm just blind today!

Any help would be greatly appreciated.

Teresa