Controls respond but won't set tempature

(Sub zero. Brand selection not finding.)
Digital display responds to touch and was set to 45 f in the fresh food section but when I press colder it displays 35f really quick then back to 45f. After resetting the fridge several times it finally allowed me to to click the set temperate colder and lowered to 35f. Wondering if it’s the display that’s defective and what part should I replace just the display panel because it’s connected with a touch membrane but when I selected to go down it responded to my touch but did not go down 1° every click until I reset it.