Struggling to add a personalization box to product page

[brittany-999]

Hi there,

I'm having issues with adding a personalization box to a product page.  I have been trying to follow this tutorial. I am using the Minimal theme.

I am at the step to "Apply your new template to a product".
It says "In the Theme templates section, choose 'product.customizable' from the Product template menu."

Hopefully I'm looking at the right spot, I am on the product page, on the right side under Online Store, there is a dropdown for Theme Template. However it is greyed out and won't let me select anything. (see below).

Firstly, am I looking at the right spot? If it is, why isn't it working? My site is live, but currently password protected (I did briefly take the password protection off to see if that would do anything, but it did not.).  I am also integrated with a Print on Demand site (Printful) if that makes a difference.

Thanks for any advice!

[NomtechSolution]

Open the "product-template.liquid" file and search for the following line of code:

{% section 'product-template-information' %}

 Below that line, add the code for your personalization box. This can be a form or an input field where customers can enter their personalization details. For example:

<label for="personalization">Personalization:</label>
<input type="text" id="personalization" name="personalization">

[brittany-999]

Hi there. I can't find that line of code in product-template.liquid. 

I also don't want to add a personalization box to every product, wouldn't changing that file do that?