It's called linking your accounts, and Google does offer this as both services belong to Google. I believe there are videos on how to do this, or you can fiddle around in either services settings. I'm on my mobile at the moment and would have directed you to some content otherwise, but I'm sure you can get around.
I did it but YouTube asked me to. I don't know if there's a way to force it.
+Jason ON hmmmmm
On YouTube, go to My channel then click edit on the right. It should then allow you to connect accounts. Took me a while to figure it out.
It's called linking your accounts, and Google does offer this as both services belong to Google. I believe there are videos on how to do this, or you can fiddle around in either services settings. I'm on my mobile at the moment and would have directed you to some content otherwise, but I'm sure you can get around.