Peugeot 308 T7 Air Bubbles - Please help

[Dwaite8076]

I recently replaced my heater core and seem to have air bubbles stuck in my coolant pipes
When I start the car, as well as accelerate, I can hear water moving briefly, so I assume that's the air bubbles in the coolant
How should I get the air bubbles out?
I've tried running the heater on max heat, low fan setting with the radiator overflow cap off, that didn't seem to help
I've also drove the car until it got hot, opened up the bleed screw to try and release air, but that didn't seem to get the air out either, coolant was coming out though...
Am I doing something wrong? Any help is appreciated!

Example of what I assume is air bubbles when I accelerate (turn the volume up)

[Dwaite8076]

Is this just the most difficult and complex topic to cover or something?
I can't get a single response from anyone regarding this issue....I assumed burping the car was straightforward but I guess I was mistaken