Whose World(s) Is It, Are They, Anyway?

Regarding the many (infinite?) worlds theory, then something I have been wondering on, is just WHOSE world is any 'given' or percieved world, anyway? I have to assume that the one I've been experiencing all my (apparent) life is effectively mine, at least from my perspective, albeit that I have seemingly little power to change or influence much at all beyond my own immediate and/ or current (again, apparent) locale, and even then only in regard to my own thoughts and immediate cause-and effect actions. But if every decision or action I've ever enacted, or every decision or action of those of folks whom could affect what happens to or around me, no matter how small, has led to a spin-off version of this world, then whose world really is this and whose worlds really are all those others? For example, when I recall how I never followed up nor maybe got a real opportunity to build on some childhood sports, especially football (the English version!) 'prowess', and yet am so led to believe that there is a world, are worlds, in which I did just that, maybe even became a professional (yes, fat chance!) then are those worlds my own also? Of course, there are many, many, more, myriad examples, of such, just in regards to myself (whom I use for personalised example only, by the way!).

I have come to think that maybe I ACTUALLY DID this or that, even achieved this or that, including possibly attaining wealth, and that although THIS ME, the only TRUE ME I could ever essentially consider fully, remains as is and being exactly where I am, having hitherto done or not done whatever, etc, then those OTHER ME possibilities nevertheless remain, and continue on.. somewhere. Right? Okay, so we can't in essence actually reach out - or even look out! - and observe these other worlds and their incumbents, ourselves, and all their altered possibilities, but then how do we consider them at all? Again, whose worlds, or 'realities', are they?

And it is with these perhaps perplexing, certainly currently unanswerable, questions and notions, that I found myself, earlier today, considering how the 'observer' apparently directly affects such [quantum] effects as the particle/ wave-function variable, as per the Double-Slit Experiment, and also that alive or dead dual-scenario of Schroedingers poor cat! Moreover (perhaps with too much time on my hands!), what I actually did, considered, was how someone, perhaps from my long-ago past, who came to find me and also 'catch-up' with how life in general had turned out for me, would of course, find exactly the what where and when there is of me to find, just as I already know it! But that HAS TO BE so, from MY perspective in the here and now, doesn't it? But what of those other versions and possibilities? Might it not be in the seeking of those answers about anyone or anyTHING, that the SEEKER becomes the OBSERVER, and so that's where that particular version of events and/ or person/people came into actuality, upon OBSERVATION, albeit not in THIS particular world? And so, would that whole new world not then 'belong' to that observer? Maybe thats why I, we, could never go there!.. Or perhaps we do, have, but we just don't know it!!