Forget about TX/RX pins.
An INA219 module has four connections on one side for 5volt, ground, SDA (A4), SCL (A5).
Those pins power the module, and send the (I2C) current and voltage data to the processor.
The other side, with the scew terminal, is for the actual current sensing.
All the current (+wire) from the supply to your project (+wire) has to run over those two connections.
So connect supply(+) to one, and project(+) to the other screw.
All grounds of all modules should be shared.
Post a diagram and/or picture(s) if you're not sure.
Leo..