How do I get Youtube to enable linking to external sites from my videos?

I’ve got a Youtube channel consisting of helpful hints on “problem A” along with product reviews on items that mitigate “problem A”.
I happen to run an online shop selling the product in question.
I’ve got viewers of my videos who are telling me that they “love this review, and I just bought the product”.
I’m all for competition, but I’d much rather be getting sales for the items I’m reviewing… which by and large, I’m not.

I thought I could add annotations to the video linking to an external site, but it appears that my account doesn’t have that turned on when I go under:

Account Features

So, any clue how I get Google to turn that on?

Okay, turned it on by turning on:
account monetization .

Still don’t have the option to add links to “Associated Website” when I do annotation, but it’s progress.
Have tried all 3 browsers I have installed, clearing cache/etc on two of those.