MY LG washer is out of balance. I have been told

The demo mode does not do what you want it to do. Demo mode allows the retailer to demonstrate the wash tumbling without hooking the machine up to water and drain, and show the spin, and allows a servicer to test see those things, plus testing of the display board, water fill, and even the heater if your model has one. Demo mode will NOT "rebalance" the washer drum. Some models have a "Spinsense" setting, and newer models have a "Tru balance" ring, which does a very good job. (no, it is not a retro-fit type drum) Your only solution is to make sure your machine is on a solid floor, level, and all legs making firm contact with the floor. Load selection and load size have a limited effect on un-balanced situations, but The biggest factor here is having a SOLID FLOOR.