I am currently planning an Issue Security Scheme. As a matter of fact I change e. g. the description of a security level while I "develop" the security scheme right in JIRA (instead of using pen & paper to plan beforehand).
The problem: I cannot even edit the description anymore after I added a security level. I can only delete it and create a new one.
Current workaround (for also keep current issues assigned to this security level):
1. Create a Security Level "Tmp"
2. Delete the Security Level you want to rename or edit the description of
3. As replacement-security level select "Tmp"
4. Create the new Security Level with e. g. adjusted description.
5. Delete "Tmp" and select as replacement-security level the newly created Security Level.
... Well, quite a lot of work for such a simple task like adjusting the description...