Before I tell you have to improve your SAT parts,I really appreciate it that Khan Academy and CollegeBoard has been able to grant newfound access to test preparation opportunities to students like myself, however there are still several shortcomings. One of those shortcomings is your lack of good explanations especially when it comes to the much harder problems in the math section where they are often so complex that I just give up on even trying to do well on the 4th section since most of your instructions like your tips and strategies cater to only the beginner with the only explanations as far as I know for the hard math sections being the hard example and the actual explanations when you answer the question. One solution to that problem that I propose could be to get some students to answer the question and as for those who answer the question correctly, you ask them what they did to be able to answer the question correctly and you share those explanations with the rest of us so that I could actually understand the explanations. You guys should also try and watch some guy on youtube called Scalar learning and take a page out of what he is doing since I oftentimes understand his explanations way more than yours as he does full length math tests from the perspective of the student.
tl;dr give us more access to more explanations and you could do that by watching scalar learning or get some students to explain how they got their answer after they done it.