Ok, I'll explain it again but using easy words just for you. Yes, today China emits the most CO2. But the US has emitted twice as much as China historically, and the total amount of cumulative emissions is causing the climate to change. We have emitted the most and this are most responsible.
That's still too many big words for you so let's compare it to a bathtub with no drain. The tub is almost 90% full and the US has added 25% of that water, far more than China. Today China is adding the most water to the tub, but the US is still adding the second most water. When it is full the US will have added the most water, twice as much as China. Who put the most water in the tub? The US.
Damn, I just realized you probably don't bathe so this makes no sense to you.
Sorry, also meant to say Gina not China so you'd understand.
Oh well, I tried.