Documentation for "Manage Permission Groups"

We are setting up two new permission groups in test environment (UAT). We are trying to assess if the new permission groups should have the boxes checked (all of them) or not. We don't know what each box does and the ramifications of checking/unchecking each box. Live Support told the best way to go about making sure the changes we make are going to have the results we want "would be planning which level of access the group would have, what specific parts can be accessed and, by studying the behavior of your current permission groups, mark the items and test by controlling a user". We would have to test after every box we check/uncheck, and if we don't know what the box does, how would we even know where to check? A much more reasonable solution would be to have PageUp documentation on how/why we'd configure each item please!