DIAGNOSIS Your device (phone, laptop) is clinging to the first eero it connected to. Client devices, not the eero network, usually decide which node to connect to.
FIX Toggle your device's WiFi off and on. This forces it to find the strongest signal from scratch, which should now be the closest eero. Do this whenever you move to a new part of your home.
IF THAT DIDN'T WORK Enable "Client Steering" in the eero app (Settings > Network Settings > Wireless Radios). This encourages compatible devices to move to the optimal node and band, but it's not guaranteed for all devices.
HEADS UP Some older or simpler devices (IoT gadgets, smart plugs) are terrible at roaming and will stubbornly stick to a weak signal. For these, you may need to temporarily move them closer to the preferred eero during setup.