Adding a dot to an existing chord

I entered a chord with a quarter note duration. After entering the chord I pressed escape to exit from note entry. I want to change the duration of the note from a quarter note to a dotted quarter note. I do not see instructions on this in the handbook or via the help feature or by doing a forum search (no criticisms of people who ask questions, in the form of accusing them of not looking for the answer). I tried selecting the chord and then clicking on the dot icon but that didn;t work. I tried selecting the chord and entering the note editor but that kept trying to change the pitch and wouldn;t change the duration. Thank you for detailed, specific instructions.