When creating a Dashboard, you can decide if you want it to be Private (for only you to see) or to enable others to view it also.
If you want to restrict access so only you can see this Dashboard, click to enable this option:
You can then Save & Exit and your dashboard will be added. No Permissions will apply to the Dashboard, as you have created it as Private, so you will be the only one to see it.
If however the new Dashboard is to be shared with others, leave the Private option unchecked:
Next, click into the second tab called Permissions.
If you are a Main Admin or have the relevant level of platform permissions, you can the select if you want other Groups of users to have View or Edit level of access over the Dashboard.
Those with View permissions can View the Dashboard but not make any changes to widgets.
Users with Edit permission can Edit Dashboard settings and Add, Edit or Delete Widgets.
* For shared Dashboards please note that changes that any user makes to a Dashboard or Widgets within will apply to all users that have access to that Dashboard.
If you do not see the relevant Group in the list to assign permissions, check this group's rules under Admin > Groups to ensure that the Dashboard module have been enabled for this Group.
You can read more about setting up / updating permissions for your different Groups here.
Item List Widget