One thing to note, with Gulf of Mexico he actually had Republicans pass a bill to do the change.
This one is an executive order. An executive order is what the name implies. It is not a law, but an order for executive agencies to follow. So while employees of agencies like FBI or IRS are instructed to call the lake as lake America, as far as the rest of the country is concerned the lake is still the Lake Ontario.
It's clearly is a stunt to distract from the pedophilia and a failed war.