By Javed Baloch | viageeks.com
sign into YouTube Studio. You can access it directly from studio.youtube.com url.
From the left menu of options given, locate 'content' and click on it.
Click on the chick box of the videos that you want comments to be turned on or off.
On top of the list of your posted videos, you would see the option of edit with a trigger button. Click on 'Edit'.
You will see a list of options. Select 'Comments'.
You will see the options of allowing the comments or disabling them. Select your preferred choice and hit update videos. That's it.
Select settings in YouTube Studio. Select community and click on defaults. Here you can turn on YouTube comments on new uploads by default.