Assign shared dashboard as default Dashboard for a Group user

[SARAVANAKUMAR]

USING JIRA Cloud

Is there a way to assign a  shared dashboard to a user group (or) roles (not the system dashboard)? 

Or if there is a way where I can disable the system dashboard.

[Jack Brickey]

you don't "assign" but you "share" with a group. if you are the owner of the dashboard just edit permissions and share w/ group. If by "assign" you mean allow users w/in a group to assume ownership permissions then no.