Tracking must be enabled for each product individually. There are 2 ways to do so: you can enable tracking while creating or editing items from the Item List, or through the Serial/Lot numbers page. Either way, the process is basically the same, except that Create/Edit Item requires you to first check the Tracking box. Let's look at the example with enabling tracking through the Serial/Lot numbers page. Go to Inventory → Serial/Lot Numbers. In the left part of this page you will be shown a list of all Inventory type items for which tracking could be enabled.
If you highlight an item that is not being tracked yet, you will see the following settings in the right pane:
Here you can choose how the item will be tracked and enable tracking for it. A product can be tracked by:
Also, you can choose how the Auto-Pick function will work for this product:
Once you've made these two choices, click Enable Tracking to start tracking this item as configured.