A good advice came in the discussion from former pro GK and main J4K Ireland coach Matthew Gregg at J4K Skool Ireland.It makes a lot of sence.
If you are watching the game from the side of the pitch, it might look very obvious for parents and coaches for a goalkeeper to react/ act some certain way.
But from the eyes/position of a goalkeeper - different things look obvious and right to do!
Therefore a goalkeeper has to go with his original decision and to be vocal to let the team mates know with clear instructions. Otherwise, listening to the sideline ,goalkeeper's hesitation causes havoc.
It is for the GOALKEEPER to decide,
with parents/coaches shouting would put INDECISION in the keeper's mind.