Editing the Product Details page

[bchocolates]

I'm quite new to the PrestaShop CMS and I've been having an issue where I can't find out -where- to edit the Product Details page in detail. Managing what appears and what doesn't.

The main page, for example, can be easily modified using Design > Theme & Logo > Homepage Configuration (ver:1.7.6.0) -- Why "Homepage Configuration" is listed under the "Theme & Logo" category is beyond me. However, I am wondering where exactly I can modify elements in the product details page itself. That is, when you click on an item in the shop, it goes to a new page detailing information about the item, as well as a purchase link. There doesn't seem to be anywhere within the administrative CMS to edit this information. Am I supposed to go to the relevant .php files and modify them directly? I initially thought, for instance, that I could go to the Design > Positions section and change it there but it seems to lack intuitiveness (see attachment).

Thanks in advance.

 

Additionally, since upgrading to the latest version from 1.6.x, I have been unable to access Customers > Customers within the CMS and receive a 500 error. I am wondering if anyone else has received this, as well as how to rectify the situation.

 

Thanks again.

Edited August 6, 2019 by bchocolates
Additional information (see edit history)