Is there anything that would prevent a admin from adjusting permissions on different user groups? So I can change anything I want below let say in the signature setting and click SAVE button. Come back to the very same page and nothing is changed. Did I miss something here?

What are the values that you're changing? They must be valid to save (e.g. you can't have -1 links in a signature) 

Please also ensure you're on the latest release (4.1.5.2).

Max lines should be ONE.

Max link in signature to ZERO.

MaxSize of image ZERO x ZERO.

Max Images in Signature ZERO.

Should be valid... I would expect there is a way of shutting down these functions.