The valve actuator switches are set, to match proper flow of water thru the proper designated systems plumbing, per the selected system the automation system controls.
I am making a presumption that you have pool/spa combo, and you have an automated controlling system? With that system... Are automated valves controlled by valve actuators.
Your question was not specific enough, therefore I have to guess as to what you are asking.
When you choose 'Pool' ON - and Heat on, if there is a demand for additional heat, the heater will come on. If it was on SPA mode when you chose the above, the valves will automatically start turning, so that water will be sucked from the pool and then returned to the pool. SPA will sit stagnant during this time.
Now here is where I am guessing...
If the water is sucking from spa but returning to pool, the system is 1/2 correct (valves are 1/2 correct) and you need to manually have the 'Suction Side' valve turn 180 degrees. The automation will not be affected... To do this, locate the Manual 3 position switch on the valve actuator. Then flip it to exactly opposite position. The switch is labeled 1, Off, and 2.
Hopefully it was not in off position... Not a problem, just a little more explanation required to set it correctly. So if it was 2, flip to 1, and vice versa. IF it was on Off then the valve was not moving when automation gave command to begin Pool usage and Heat ON. Flip the switch until you get the flow of water Sucking from pool.
Note*** The valve handle has a 'Flag' opposite the handle as part of the handle, it's semi triangular , and when that flag is over the pipe, that pipes PORT is Closed! So if you know what the two pipes going into your three way valve, then into the pump are because they are labeled, then it is easier... Flip the switch until the flag part of the handle is over the pipe marked Spa.
The same explanation goes for the return side valve, if water is returning to the spa, and automation is set for 'Pool' operation, you will know this either because spa is spilling over into pool, or the flag portion of the valve is over the pipe marked Pool. That flag portion needs to be over the pipe for Spa Return.
Notice the little switch on the right side of pic attached... Near the word Torque. And the triangular part of the handle as well.