allow users to only view their own incidents and prevent them from changing them once created

Hello sap community,

i have a question regarding ssm 7.1. My keyusers are only able to see the necessary menus in Web_ui (Solution Manager - IT-Servicemanagement / CRM_UI) to create incidents and search for incidents.

Yet they are able to search for all incidents available. (by providing no specific search paramaters)

They are also able to open incidents of other keyusers and are able to change basically everything within. (Priority, Service team, status,...) Only Helpdesk users should be able to change .. lets say priority after an incident has been created.

How can I accomplish the following objectives:

a) Deny them the ability to change priority and pretty much everything else once the incident has been created?

b) performing a search that allows them to see other peoples incidents, just the ones created by themselves (maybe by forcing a certain filter that only allows them to search for incidents "created by me" ?)

any advice on this topic is highly appreciated

regards

CB