You need to familiarize yourself with the concept of dataflow programming.
If loops need to run in parallel, you cannnot have wires going from one loop to the other. Any such wire creates a data dependency that forces execution order.
In addition to the execllent pointers given by Sergey and Christian, I want to mention one more thing
Since you are performing a simultaneous AI, AO operation, I suggest you have a look at examples given in find examples>>H/W input output>>DAQmx>>Synchronization>>Multi Function folder and have a look at "Multi function Synch AI-AO.vi"
you will be better off by following this logic.