The fastest way I have found :
Click Settings button on Remote
From Settings screen Popup, Select PICTURE
On that Picture screen that pops up, select ASPACT RATIO
On that Aspect Ratio Screen that pops up, select USER SELECTION
On that USER Selection screen, choose which aspect ratio you want (I toggle between Original & 4-way Zoom to get the bottom LOGO(s) and Crawl off the screen to prevent burn-in)
Once set, you have to click the left arrow return button on the remote to get out of that Aspect screen. Then you can just click anywhere on the TV screen to get rid of all the settings screens.
So THIS is my issue I wish the developers would fix. It takes way too many steps to set Aspect ration now under the latest WebOS version vs the older LG OLED WebOS software.