How to Add Subscribe Button On All of your YouTube videos
Here are the steps to create a subscribe button using the Branding Feature:
Click on your Profile Image
Click Creator Studio
Click Add a watermark
It says “for best results, use transparency and just one color.”
click on file
We’ve got the name “subscribe’
Now we’re going to select PNG transparent full quality, 3KB
Save to your desktop
Choose the file you just created
Click save again
It says “showing on all your uploads”
Choose “entire video” from the drop down
Check that the subscribe button goes to the channel. If nobody has subscribed you’ll see the subscribe button at the bottom of your YouTube Channel banner.
The subscribe button will appear in the top right corner of all your uploaded videos across all devices.