Calculating torque from yield stress understanding

Hello,
I'm new here and so if I've put this in the wrong section or anything, please let me know and I'll fix/change whatever needs to be done.

I just wanted to see if someone could help me understand something.

When choosing a torque value, is it just ~90% of the yield stress of the material of the torque rod? I have to design a torque arm that needs to withstand a certain volume before hitting a switch and need to decide where to put the force/hang the volume along the arm. I already know the force, and the material of the torque arm and rod, so need to chose a torque value so I can figure out the distance along the arm for the force. Sorry if I'm being a bit vague, I want to solve it myself, but am just having some trouble with understanding things. If you need more info, please let me know.

Anyway, I found the yield stress of the material of the torque rod, it was around 185MPA. I just plugged that straight into torque = force x distance. Is that right? Should I have converted that to Pa? Or because torque is in newton meters and stress is in pascals and they're not the same right, so I need to do something else to it? I'm not sure what to do. By doing that (putting 185 into the equation as torque) I got a really small value, so I think I've done it wrong and am currently lost.

Could someone please point me in the right direction?