Play lots of games to get your bonding up on yor V5.
V4's usually ask for time-outs and praises. What I do is when they call for attention, sometimes trhey don't need attention, so you give them a time-out. That drops a happy heart but gains a training point. When your V4 calls for you and its back is turned, OR if its crying, I praise it. Thats gains a happy heart AND a training point.
I heard that you're supposed to give your tamagotchi a time-out when it calls and its back is turned. But thats not true. I tried that and it just emptied a happy heart. The training points didn't even go up.