You may use User Filter or Password Protected Dashboards. I think in Your case you may use Password Protected Dashboards as you have 3 People and 3 Dashboards.
Create a dashboard.
Drag a Horizontal Container.
Drag all the sheets one beside the other in the container.
Get the Login IDs of the users.
Create 2 calculated fields.
U1_Filter as U1 = username()
U2_Filter as U2 = username()
U3_Filter as U3 = username()
Drag the filters in the respective users sheet and select True for each.