Bulk upload inventory for existing SKUs

[contemporary-equestrian]

Hi,
We have tried updating the bulk inventory via template file for existing SKUs but approx. The list of 1800 SKUs has not been updated properly. and we are this way to updating the inventory for existing SKU as below:

Uploads->  Select a template -> Fill in the template -> Proceed to upload

Please check and confirm how we can update the inventory for all existing SKUs.

Thanks