There are two ways to do this:

1. Editing the product directly via the product editor, or
2. Importing a spreadsheet (bulk update).

Using the product editor:

1. Go to Products > Products / Sku variations.
2. Open/edit the product by clicking on it.
3. Click the toggle labelled Has batch tracking to toggle the feature on/off.
   
4. Click Save.

Via a spreadsheet import (bulk update):

1. Export the current list of products into a spreadsheet.
   1. Go to Products > Export data.
   2. Select the data type Products and ensure you include all available columns in your spreadsheet to download.
   3. Click Download.
2. Edit the spreadsheet.
   1. In the Batch tracking column, enter yes for each product you want to enable the setting for (leave blank or enter no to disable).
   2. Save the file.
3. Import the updated file.
   1. Go to Products > Import data.
   2. Select the data type Products and upload the updated spreadsheet, then save.

Batch numbers can be captured during two processes:

1. Receiving purchase orders
2. Ship out / dispatching sales orders

Receiving purchase orders:

1. Go to My account > Settings > Purchases > Options.
2. Click the toggle labelled Capture batch numbers to turn the feature on/off.
    
3. Click Save.

Shipping out / dispatching sales orders:

1. Go to My account > Settings > Sales > Options.
2. Under the Shipping section, click the toggle labelled Capture batch numbers to turn the feature on/off.
    
3. Click Save.

To view all recorded batch numbers, go to the batch numbers page (Products > Inventory control > Batch numbers).