Microfibre is very quick absorbing but not very good at storing the liquid. For this reason you should use your microfibre inserts on top then hemp or bamboo which are excellent at 'storing' the wee underneath. This was the only way I got pockets to work well.
As others have mentioned play with folding to best suit the fact that he is weeing at the front (as boys do!). Also do you make sure his willy is pointing down when you change him (sorry thought I'd ask as I didnt' know I needed to do that with DS1
I really hope you can get them to work with the right inserts. Do remember that babies change shape, often rapidly so what doesn' work well one week will be fab a few weeks later.