How do I manually use cellular if my wifi or iPhone connection is too weak. Also, why does the watch not use cellular when iPhone is in airplane mode and wifi is off on watch? Why am i paying for it???

How do I manually use cellular if my wifi or iPhone connection is too weak. Also, why does the watch not use cellular when iPhone is in airplane mode and wifi is off on watch? Why am i paying for it???

When my iPhone is a weak signal because its across the house through many rooms, and the WiFi isn't working well, I want to use my cellular data I pay each month for manually. I try this by doing the steps outlined above, but mine doesn't work whatsoever. The watch continues to say "Disconnected" and doesn't connect to cellular, even though I pay for a plan thats active, and the cellular switch is toggled to on for the watch.