How to add "Subscribe" just underneath and in the description of a video in Youtube?

Youtube offers many ways to give users who watch a video a hint to join the channel.

The ones that I know how to set up are:

1. As an icon on an end screen
2. As a link in the video description
3. As an icon associated with a watermark

I'm trying to figure out how to add the other two options, which I know they exist but I have no idea why they don't display in my channel:

1. As a word "Subscribe" next to the Like button
2. As an icon with a link next to the Videos and About icons

How do you add those? Does your channel need to be monetized for those to appear or to be enabled?