I'm shocked that they made your left arm the right button and the right arm your left button. Makes no sense whatsoever. How do I reverse them? I looked everywhere and came up empty everywhere. 

Can you not just change the controls in the options menu?

They don't let you change button assignments in the control menu? Hmm... only method I can think of outside the game is to go to your mouse settings in the control panel, and check the box beside "Switch primary and secondary buttons" under the Buttons/Button Configuration tab each time you want to play.

You can 100% change it in the keybindings menu, I know because i thought same as you at first and changed them around only to find that my reflexes are still wired with "push right mouse button to shoot"

Personally, I would probably reset the plasmids to my side button on the mouse rather than the right button, then switch my right button to ADS. 
 
Nonetheless, thank you for pointing this out.

Strange, Tennmuerti, I heard on a games podcast that the guy had to go inti the config files and reverse it, but that his brain still wired it backwards too. Maybe I mishead.... I'll go check.  
 
Edit: Yep, you're right. Thank you! They put the left mouse action and the right mouse action on two different pages in the options, and the way they were labeled threw me off. Thanks for the rapid responses everyone!