How does the two slit experiment work?

As far as I understand the two slit experiment one explaination is superposition, 'cause when they just observed the screen the electrons acted like a wave, not just hitting one spot but hitting all spots with varying intensity (which is what created all the lines), but when they tried to track individual electrons they just hit one spot. The conclusion that they drew (one of them, as said in the comments the many-world is another slightly different interpretation of superposition) was that when unobserved, the electrons went down every possible path, just like a wave would.

Hope I could help