Products are shown on category pages based on sort criteria specified under Settings > General Settings > Results Sorting: Primary Sort Key and Results Sorting: Secondary Sort Key.
The 3 options are:
- Alphabetically - Sort from A to Z
- Price - lowest to highest
- Sort Code - lowest to highest
There are two sorting keys; the system will apply the first key, then use the 2nd key for tie breaking.
Sort Code is specified by product for each category under Products > Product Catalog Manager > Product Editor > Categories.
You can also edit each product's category's sort order via Import/Export.
The customer has additional sort options on category pages, but these are the only default settings for category sorting.