2022 version
Just wanted to share what I tried to update Julia on my windows and it worked just fine.
I added UpdateJulia package and using that (using UpdateJulia) I updated the Julia version on my PC by update_julia():
Open Julia Package manager and type in the following commands one by one,
]add UpdateJulia
using UpdateJulia
update_julia()
Remember: simply typing ] will bring you to pkg mode in REPL, and by delete (mac) or backspace (windows) you get out of it.