Every air fryer cooks differently, so check on the sandwich often to make sure it doesn't burn. Or to make sure it's cooked enough, just add extra time. If you slice your cheese thick, then it will need more cooking time at the lower temperature to melt the cheese all the way. If your bread is really thin, it will blow off in the air fryer because of the hot circulating air. Use toothpicks to secure the sandwich during air frying. Remember to remove the tootpics before eating.
Lay cheese in between bread. Butter outside of bread with butter. Lay sandwich in air fryer basket. If needed, use two toothpicks to secure the sandwich together by sticking it through the sandwich.
Air Fry at 360°F for about 3-5 minutes for the cheese to melt.
Flip the sandwich and increase heat to 380°F to finish and crisp the bread. Finish air frying for about 5 minutes or until the sandwich is to your preferred texture. Check on the sandwich often to make sure it doesn't burn (different breads will toast quicker or slower than others). Allow to cool a bit before biting into the yummy grilled cheese sandwich!