You cannot configure a dashboard that has been shared with you. However, you can create a copy of the board to customise it.
You can create a copy of the shared board by following the below steps:
Go to the “My Sourcing Boards” page where you can see all your sourcing boards.
Locate the desired board that has been shared with you and click on the three dots on the top right corner. Click on the "Copy this board" option from the drop-down.
A pop-up window appears that the Copy of the Board has been successfully created
Click on the "Take me to Board Settings" button which will redirect to the Configuration page where you can change the desired details of the board and then click on the "Save and take me to my board" button to implement the changes.