Practical checks
Check the TV model and year, then the apps available in LG Content Store. Choose a compatible app listed in checkout. Do not install an Android or Fire OS APK on the TV merely because it has the same player name.
Prepare information before making changes
Start with the exact model number from TV settings. Keep a photo of the app identifier for your own local comparison with the account. If the app is missing from the store, note the store region and ask for a compatible recommendation; a Firestick APK does not replace a webOS app.