Help me return BTC to its rightful owner.

I just checked my wallet and I found out it has some five figure amount worth of BTC. I know it's not mine, I've already talked to my friends and family and none of them have sent me any BTC. I'm a newbie so I'm sure some user must've made a mistake when transferring their coins. How can I trace the transference and return the BTC to them?

Edit: Some people say I should be able to see the sender's address. But unfortunately that info is nowhere to be found on my app.

The only thing that's different is that now I have some BTC that I didn't have an hour ago. So if you could be more specific or provide another tool to trace the transference that'd be helpful.

Edit2: I won't accept any PM guys. You know why.

Edit 3: No. I don't feel like an idiot for trying to return the money. It might be some change belonging to some rich person or it could be the life savings of a family, so fuck off, I'm giving it back to the owner.

Edit 4: I've checked and the address that sent me the BTC is actually an exchange. However you've told me not to send it to an exchange. What should I do then?

Edit 5: Ok so you people are telling me, that if the address is from an exchange they will keep the money. That won't do. I guess I'll just donate the money, cuz I won't keep it. Thanks to all of you who've been kind and tried helping me to return the BTC.