CZpajska to enable dual channel mode, remove the 32gb stick from the motherboard.
Make sure the two 8gb sticks are in memory slots A2 and B2 on the motherboard. Usually they're the same color.
Dual channel memory needs two matching memory sticks to work. The 32gb memory stick is in single channel mode because it doesn't have another matching 32gb memory stick.
Even if there was a matching 32gb memory stick, there's still a size mismatch between the 16gb memory sticks and the 32gb memory sticks.
For best memory performance and stability. All the memory sticks should be the same size, speed, and made by the same manufacturer.