So if we have past lives and future lives, how we decide where we will born?

Sometimes I see these dreams, that aren't mine.. or they are but aren't like they are memories... As a child i was the goofy one, always explaining adults something how i don't belong here really, i chose you to be my people etc. And as a child i use to have also these dreams, some of them were horrible nightmares so vivid and realistic (all the pain, horror), some of them were nice (friends, love).

So this brings me to my question: When we are children do we know how things are? Is it the pressure of the society when we stop believing or forget the truth?

Is there anything that would help me remember my past lives? Can anyone here tell me about my lives?