Previously, every channel you created needed to have its own Google account login.  If you’re a creator who manages many channels, you might even have a spreadsheet to organise the various email addresses and passwords that you use to log in to your channels.  
We made a significant improvement to the multiple channel management experience recently when we launched the option to connect your existing channels to a Google+ page.  Channels that are connected to a Google+ page have enhanced channel management features, allowing you to manage up to 50 channels with a single login. Multiple individuals can manage your channel with their own logins.
Now, when you sign up for a new channel you’ll have the option to connect it to a Google+ page.  This will allow you to create new channels using a Google account that you already use to manage your other channels and Google+ pages.  This is a significant simplification of the channel signup process. We encourage you to take advantage of this when you’re creating new channels in the future.  
Create a new channel connected to a new Google+ page
1.Sign in to a Google account that you use individually – maybe it’s a Google account that you already use to manage other channels and Google+ pages, or it’s the Google account that you use in the YouTube Content Manager.
2.Go to http://www.youtube.com/channel_switcher and click Create a new channel.


 
3.Provide a name for your new channel and Google+ page, and click Done to complete the signup process.  Remember, channels connected to Google+ pages can have names that include spaces and punctuation if that’s what you want.
Create a new channel connected to an existing Google+ page
1.Sign in to a Google account that is the manager or owner of the Google+ page with which you want your new channel to be connected.
2.Go to www.youtube.com/channel_switcher and click the name and avatar of the Google+ page for which you want to create a new channel.


3.You’ll be asked to confirm that you want to create a new channel for this page, so click OK to complete the signup process.
Additional tips for your new channel
●     You can add other people as a manager of the new channel and page (instructions).  Remember, we encourage everyone to use their own logins to manage channels, rather than using shared logins!
●     Your new channel URL will look something like the URL below, so if you’d like a custom URL that is easier to remember, follow these steps: www.youtube.com/channel/UCNimhyukHP5tdka3a9zi9Nw