1. Apply the update to variants that have the same product identifier
By default, it's set as false. The update would not apply updates to variants with the same product identifier unless it is set as true.
For example, if the feed file has 5 products with the same SKU then the update will apply to all 5 products.
2. Track quantity by Shopify.
By default, it is set to true. By enabling it, it will set all the variants updated will be set the track quantity by Shopify.
3. Low Stock level
Determine the low stock level and turn on the notification in the preference tab. You will receive notifications through email on products that are low stock levels.