Press Tab, Shift+Tab, or the arrow keys until you reach the field.
Use the editing keys to edit the field's contents, then type the replacement text.
Arrow key--move the text insertion cursor
Backspace--delete the character to the left of the cursor
Delete or Delete char--delete the character to the right of the cursor
Control+Delete char--delete from the cursor to the end of the line
Press Control+Tab to move keyboard focus out of the text field.