Fill a large pot with heavily salted water and bring it to a rolling boil. Add elbow macaroni and cook until al dente, about 8-10 minutes.

Remove the macaroni from heat, drain it in a colander, and rinse under cold water for 30 seconds.

In a medium mixing bowl, combine mayonnaise, yellow mustard, apple cider vinegar, sugar, salt, and pepper. Whisk until smooth.

Gently fold the cooled macaroni into the dressing until fully coated.

Add chopped red bell pepper, red onion, green onions, and parsley to the mixture. Stir gently.

Cover with plastic wrap and refrigerate for at least 1 hour to allow flavors to meld.

Before serving, stir the salad and adjust consistency with milk or more mayonnaise if needed. Garnish with parsley.