How to edit one specific row/tuple in Server Management Studio 2008/2012/2014/2016
Step 1: Right button mouse > Select "Edit Top 200 Rows"
Step 2: Navigate to Query Designer > Pane > SQL (Shortcut: Ctrl+3)
Step 3: Modify the query
Step 4: Right button mouse > Select "Execute SQL" (Shortcut: Ctrl+R)