The status will not be modified, @VAlentina2.

As long as you've only added a file on the transaction, that won't affect the status of the invoice. 

You'll receive this notification, "The transaction you are editing is linked to others. Are you sure you want to modify it?" when you've made any updates to the current transaction or invoice. You can click on Save to record the changes that you've added. 

You can view all the uploaded attachments by going to your All Lists. Check this article for more information: Attachments in QuickBooks Online. 

I'm always here if you have any other concerns. Have a wonderful day!