How can i change the permissions of a group that allready has been set to an permission. I have a group with the permission READ. I want to change that group to EDIT. How can I do that?
You can navigate to the site setting and under Users and Permission, select site permission, then select the group which you are going to change the permission level and on ribbon select Edit User permission as mentioned in below image
and Here you can change the permission from READ to EDIT and hit OK,then you can see that mentioned group permission level would be changed to EDIT