How safe are refunds?

[Silaynite]

Hey, I was thinking I do an refund as I've never done anything like that before for amazon, to get a laptop as I need it for uni and upgrading my pc through getting a new graphics card instead of my 5 year old 1050ti, I've gone through it a lot and it seems pretty legit and safe, but only part I'm sceptical is that you have to give your username and password to them and they have access to all your details, so I wanted to ask what were other people's experience with getting a refund