Well they got you.. To do a balanced flow from each bubbler to match each other they should have been ran separate with a Jandy Valve on each.. You do not have a lot of options and really only 2..
1. turn your VS pump up or down to adjust the flow
2. turn the Jandy Valve to adjust the flow..
You will not be able to adjust each bubbler to do its own thing... They will never match like you are wanting... The problem being as the water flows through each bubbler the pressure is different for each one.. The last one will have much more flow than the other 2.. I think that is what you are seeing...
A Video may help..
Wish I had better news...