Frequently encountered problems
For more information visit the Shopify help page

Footer:
Payment icons not showing although enabled:
If you have no payment method selected on your store, you will not see the icons.
Once they are added the logos appear automatically.

Product page:
Have the right column stay fixed when scrolling down until reaching the end of the images on the left:
The right column stays static, when the descriptions is a certain size, but once it surpasses that size it won’t stay static.

Here is a screenshot of the explanation in the Brooklyn theme docs:

Cart page:
Cart page doesn’t show the plus and minus symbols, but a selector simbol when hovering over the quantity number:

The cart displays the selector symbol when set to page and the plus and minus symbols when set to drawer view.

In the theme customizer go to Theme Settings and click on Cart page, select the cart type:

Product page:
Display product images as thumbnails instead of image scroll:
In the theme customizer go to Product pages and in Sections select Product pages.
For the thumbnail display in Image display select Thumbnails

Actions > Duplicate

 

Collection pages:
Grid with only two columns

 

What about the product images opening in full width in lightbox mode?

Cart and Checkout are quite limited for what can be edited for security reasons.

 

change the theme style

Zoom apps

change the wording

https://help.shopify.com/en/manual/using-themes/change-the-layout/change-wording