DIAGNOSIS You're right to be careful. Using the wrong cleaner or cloth can damage the anti-glare coating and leave permanent streaks or haze.
FIX Here's the safe, step-by-step method. 1) Unplug the TV. 2) Use a dry, soft, lint-free microfiber cloth (like for eyeglasses). Gently wipe the screen in a circular motion to lift dust. 3) If smudges persist, dampen a second microfiber cloth with distilled water only. Wring it out so it's barely damp, not wet. 4) Wipe the screen gently, again in circles. 5) Immediately use the dry cloth to buff the area dry. Never spray liquid directly on the screen.
IF THAT DIDN'T WORK For stubborn spots, you can use a 50/50 mix of distilled white vinegar and distilled water on your damp cloth. The mild acidity can cut through fingerprints. Always follow with a dry buff. Never use more than this.
HEADS UP Never use window cleaners, alcohol, ammonia, or abrasive cloths (paper towels, old t-shirts). The Omni QLED has a semi-gloss coating that those chemicals will eat away. Also, avoid pressing hard, especially on the edges.