Fortunately turning off conversation mode is easy to do.
In your inbox, find the "Filter" option on the right and click the little arrow to get a menu. Then find "Show as" and choose "Messages" instead of "Conversations". To turn them on again, just do the reverse. It's that easy!
One thing to note is that if you want to organize your sent items the same way, you do have to repeat the process. The setting only affects the folder you set it on.