With shillelagh, do you have to use your spellcasting modifier?

Shillelagh states "For the Duration, you can use your Spellcasting Ability instead of Strength for the Attack and Damage Rolls of Melee Attacks using that weapon, and the weapon’s damage die becomes a d8."

Does this mean you have to use the spellcasting ability, even if Strength is higher? I interpret "can" as giving you the option.