Shopify notifies my customer automatically when a digital attachment is updated

[My3DShop]

My shopify store sells items that are digital attachments to downloadable files.

Sometimes, we need to update the attachment, but that doesn't mean that anyone who has purchased it should automatically receive the updated attachment.

We have found that when we update the digital attachment, Shopify notifies everyone who has purchased that item and invites them to download it again.

How can I switch off this notification? In which settings might I find it?

Many thanks in advance.