How do I get my bot lane to play safe

Win lane almost every game.

Doesnt matter, because when my bot lane feeds = usually means autolose.

I try to tell my bot to play safe when I'm fed, but they usually end up dying anyway. (Keep in mind, I play top, so all that I can really do in lane is win it and grab a tower / help my jg)

You'd think this would be a non-issue at Diamond, considering I struggled through this problem my entire climb, but it is actually getting worse.

How the hell do I convince my bot to not overextend all the time / play safe?

EDIT: I have tried bribing them with RP, but even that doesn't work.