The local variables window is opened using View|Locals. The local variables window displays the contents of the local variables at the currently selected stack frame.
The set of local variables that are displayed is determined by the stack frame that is selected in the stack window.
Variable values that changed between stops of the program are displayed in red color.
The values of most variables can be changed. For this purpose, press F2 while the input focus is in the window or choose Edit value from the context menu. Then edit the value and hit Enter. Note that you cannot modify the strings that char* values point to in this way, just the pointer value.
Using the context menu you can move the active variable or structure member to the watched expressions window.