FYI to LG OLED EF9500/EG9600 TV owners, since apparently software updates are not appearing via network update check. (And if you're happy with your current version, wait on updates since backflashing these is complicated.) Recent 04.20.75 updates (no dates listed) for LG OLED models 55EF9500/65EF9500 and 55EG9600/65EG9600. There may also be updates for UK equiv. models on the LG UK support sites. (Odd, when I checked the US 55EC9300 model support page today it no longer had software updates listed, but original 55EA9800 still does, and so does later 55EG9100 model. I think there's been updates for those recently but have not kept up with versions.)
The LG support pages have a guide to updating via USB. (Basically unzip the download file and copy it to a "LG_DTV" folder in the root of a FAT32 formatted USB flash drive.) Once connected to the TV's USB port, it will prompt that an update is found. To see progress, go to TV's General info menu and select "About this TV" item IIRC. Be patient as when I saw the .60 update (from .kr site) applied the progress bar stayed at 99.9% for about a minute.
OS X Disk Utility (at least on the 10.6.8 sample mac with 16GB thumb drive) FAT formatting is FAT16, which won't be recognized by the TV. Flash drives formatted by the TV were not readable on that mac (assume NTFS formatted by TV?), but FAT32 was. This apple forum thread has an example terminal command to force FAT32 format, but ensure you ID the correct drive from the diskutil list.
(Until 4.20.75 was posted, the USA LG site update downloads were far behind the .kr site (4.20.08 was previous latest at US site) and some think 4.20.60 from .kr site (and later versions I assume) improved BT.1886 gamma curve near black and improved motion performance, but that has been debated by some. Includes WebOS and probably app updates also.)