This tutorial explains how to change your youtube profile picture that is shown on your profile main page and with your videos. The profile picture of youtube is sort of avatar for your profile and identity.
If you want to change your youtube profile picture, which is displayed as the display picture(dp) on your youtube channel and also as the image on your youtube profile, do the following:
1. Goto youtube.com
2. Goto Account (from top menu on youtube page)
3. On left menu, click account setup
4. Select Change Picture
Hope this helps you in changing the profile picture on youtube.com profile of yours. So go on and change your avatar on your youtube channal.