The shortcut Ctrl+D is to copy the contents and format of the topmost cell of a selected range into the cells below. Please see below for details:
Step 1: Select the data range you want to change, e.g., the data range A3:C6;
Step 2: Press and hold the "Ctrl" key, then press the letter "D"; all the rows are now having the value of the first row;
In case you do not like the shortcut, you can just use copy and paste command.
Step 1: Select the values you want to change to and press "Ctrl+C" to copy;
Step 2: Select the data range you want to change;
Step 3: Press "Ctrl+V" to paste with the new values.