How can one add an Epic link to a JIRA issue?

I found that answer by Thomas B:

Go to the story that you wish to add to the epic and follow these steps:

1. Edit > Epic Link > Click the drop down and select the Epic Link that matches what you want

2. If Epic Link is not showing on the Configured Fields, follow these steps:

   1. Edit > Configure Fields (top right) > Select Epic Link

   2. If Epic Link isn't shown, click "Where is my field?"

   3. Scroll down and find Epic Link

   4. Click on the blue hyperlink that says "....Screen configuration

   5. Login as Admin

   6. Select the Epic Link Field and repeat step 1

However:

• Epic Link is not showing on the Configured Fields.
• In Edit > Configure Fields (top right), I don't see "Epic Link".
• I don't see "Where is my field?".

How can one add an Epic link to a JIRA issue?