Hi, if you look at; https://www.youtube.com/watch?v-i7W2ry7MZ2k there are some good videos showing how to prune Vaccinium corymbosum, {blueberries}.
I think the plant in the top pic especially, may need a larger pot, don't forget to use ericaceous compost, Derek.

Blueberries do much better grown in the ground rather than in pots...

Mine dont MG. They are warmer in large pots, and the Ericaceous fertiliser watered in reaches all the roots.
I took advice from the people down in West Sussex who grow them. Just trimmed off 2" of each stem after fruiting. Was picking alternate days from early June to end of September. Saved them in little plastic pots in the freezer.
They lasted until February, used in a Trifle twice weekly.
If the plants get too big I will pot on into cheap builders buckets, after making drainage holes. Our GC has them for £1.99 easier to lift with a handle on, than larger pots.

Thanks for the advice. My garden soil isn't naturally good for blueberries so that's why they are in pots. I can be sure they all receive ericaceous fertiliser. The videos suggest cutting all old wood down to soil level. My blueberry in the second picture only has one stem. If I cut it right down will new growth appear?
I really appreciate people taking the time to try to help me.

No, cutting it down will retard its growth. Just trim about
2" off the branches, and feed with Ericaceous Fertiliser
every 6 weeks. You should have fruit by June.
Remember to rig up fruit netting over it to keep the birds off.