Add a custom URL for youtube
 

If you had or have a traditional YouTube username on your channel, then you unfortunately can't add a custom URL or change your URL. Your channel already has a URL associated with your old username, like the following:
http://www.youtube.com/user/USERNAME

When you create a new YouTube channel using your Google identity, you'll have a default unique URL that looks something like this:

http://www.youtube.com/channel/UCNimhyukHP5tdka3a9zi9Nw

You can see that it is quite complicated and hard to remember. If you'd like a simpler URL, you can add a custom URL to your Channel. To add a custom URL, use the following steps:
1.Make sure you're signed into YouTube, and go to your advanced account settings.(https://www.youtube.com/account_advanced)
2.Under Channel Settings, click Create custom URL.
3.You'll then be able to choose the URL you want. Note that you can't choose a URL that someone's already chosen. Once you've chosen your custom URL, it will appear like this:

http://www.youtube.com/user/CUSTOMURL

Once your channel has a custom URL, it can't be changed. Choose carefully!