DIAGNOSIS Fingerprints and dust on the anti-glare coating. Using cleaners with alcohol or ammonia will permanently damage the matte finish.
FIX Power off and let the screen cool. Use a dry, soft microfiber cloth. Gently wipe in one direction with light pressure. For stubborn spots, dampen a second microfiber cloth with distilled water only. Wring it out completely so it's barely damp. Wipe the screen, then immediately dry with the first dry cloth.
IF THAT DIDN'T WORK For adhesive residue, use a tiny drop of isopropyl alcohol (70% or less) on the microfiber cloth. Test on the monitor's bezel first. Immediately wipe clean and dry. Avoid the screen surface if possible.
HEADS UP Never spray liquid directly onto the screen. It can seep into the panel edges and cause permanent damage. Always apply cleaner to the cloth first.