I found a solutuon guys! if some one needs this, well i found out, that lg don't like 10bit normal color profile on cameras, like dji and don't like HEVC codec... i took me like half a year to understand this...
ok if you having trouble to play your videos on youtube in 4k50 or 60fps and it gives you only 1080 or 1440p. then you need to turn off the 10bit normal color profiles and export your videos in old 264 codec, that's will cure this... i will never buy lg tv again. if they will run that stupid webos. ANDROID don't have this issues.