Nobody knows where the soul resides. There has been a lot of conjecture throughout the ages on this so you are not alone in wondering.
Foremost, the question isn’t going to be resolved easily, since the soul is a spiritual thing and doesn’t have a physical form.
Confusion exists in the very terminology you use. Is the soul our spirit? Is that the same or two different things? Is there a “life-force” that has no physical characteristics attached to our bodies? We understand that animals do not have immortal souls but when they die, this “spirit” leaves them, and this is how we know they are dead. But is this a soul? So the question remains, for the human who has an immortal soul - is this separate from the spirit?
However there is a link to our physical being and our consciousness. How this link occurs nobody knows.
All we know is that when we die, the soul separates from the body awaiting reunification with the body at the Last Judgment. That this rupture occurs presents the logical conclusion that there is a relationship between the spiritual and the physical. But what that link is, is anybody’s guess.
This appears to be an unanswerable question - we may find out after we get to heaven just how this works. So until then, I’m ignoring the conjecture. If there is no way to ascertain the answer, I’m leaving it alone.