If you are a subscriber or an analyst, you only have access to your copy of the dashboard, so you don't have to worry about changing other copies.
However, if you are a publisher or an admin and you want to access only your copy of the dashboard so no changes are made on everyone’s dashboard, first check if you are on your own copy by scrolling to the top of the page and checking if this is at the top:
If you see the above bar you are connected to the master dashboard. If instead you want to access your own copy you need to log out and log back in. You should be redirected to your copy of the same dashboard. Otherwise, you can find your dashboards on the top right of your page.