I also find it easier to pump on massage mode rather than expression mode. But some people find that expression mode works better from them. There is no 1 setting which fits all. It is personalised. I think you have to check the pump parts and see if there are any tears in the duckbill valve. The pump parts will affect the suction so you have to check and change regularly if there is high usage. I will massage first, do breast compression while pumping. I usually pump for 20 min maximum. Try to think of your baby, smell clothes or something to have letdowns. To produce more milk, consistent milk removal is the best so you need to pump every 3-4 hour without fail. Can try eating oats to boost your supply too.
I think it varies from person. I had more milk expressed on the maximum strength with the highest frequency for that strength on expression mode. I will use the massage mode for like less than 1 min b4 switching to the maximum strength to save time. Milk supply takes a month plus to kick in for me. First week is like 40ml for both but gradually, can get 200ml each boob. Just rest well, eat well and pump more.