Youtube full HD lack

[Deathrow002]

I'm use Sony Xperia XA 1 plus it's really good phone for me but when I watching YouTube on full HD it running lack but however I already cleaned the cache and have reset factory my phone less than a month pls help me 😭

thanks 

[Uliwooly]

@Deathrow002 

Are you on data or wifi? how fast is your internet connection?

[Deathrow002]

I used Wi-Fi and it can watch 4k on my computer