How to maintain connections in a secondary node when main node fails

I have a VS with a pool of two servers, that only sends traffic to one of the servers, because I had configured in the pool the option "Priority Group Activation" in 1, and I also had set each node in a "Priority Group". The node A is set with "Priority Group" 2, and Node B is set with "Priority Group" 1. This is wotking well, the traffic is sent to Node A always unless this node becomes unavailable, in which case traffic is sent to node B. However, when node A becomes available all the connections are resumed to node A, but I need the traffic to stay in node B until I manually make the change.