If you created a YouTube channel when Google+ was merged with YouTube, it likely that you have URL name similar to something like this:
www.youtube.com/channel/UCRh11WUclhicHiD9MwHd2rg (note: im not singling this person out, im just using this as an example of the URL that is used)
so if you want to change it to something more easy to remember just follow these simple steps:
Go to your YouTube settings. you will see overview.
In overview go to account information and you will see advance under the email you have for your account. click the advance button.
You will then see something asking you to create custom URL.
If you are having trouble following my instructions, here is a video on how to do it. Video is by ThatTechChannel