Default Grafana IAM user in openshift can only view the status of pods.
To enable the user to be admin. Here is the steps:
oc login to openshift
oc project cluster-monitoring
oc get pods
login to the pod of grafana
oc rsh grafana-59b4db9df-*****
find the grafana db location
cd /var/lib/grafana
sql to the db
sh$ sqlite3 grafana.db
find the user you want to add to admin
sqlite> select id, login, is_admin from user;
update the user to admin
sqlite>update user set is_admin=1 where id=*;
Relogin to Grafana Web UI and your user can access this Dashboard as admin user.