Hi, all. Please help 

I have an issue here with my salesforce trailhead account, Ideally I must be able to connect to my company custom domain, I do all the necessary steps of connection I did the following:

Profile > Settings > Public Profile-enabled > Connected Accounts > Connect > Use Custom Domain – I entered the Domain the username and password were required > I entered them on one occasion the system then takes me back to the screen where username and password is required, on one occasion it passes straight to my trailhead playground and not my profile and it does not prompt me enter my company details,

Now whats strange about my username is that every time I change the connected trailhead playground the username changes, would you please assist me with this issue so that I can be able to appear on my company leadersboard, I have been struggling with this thing for quite some time now,

Your help will be highly appreciated