My dear, Rome was not built in one day. Parrots eat what they are used to eating and it takes time for them to try new things. And you need to refrain yourself from arriving at conclusions that might be just in your head. Banging a bowl is not necessarily a temper tantrum, they do it to amuse themselves, too (and please do not tell me you know your parrot because none of us really do no matter how much experience we have). And parrots have no difficulty eating small seeds, their beaks are incredibly able to peel the smallest things (my cockatoos eat a budgie mix with no problem and their beaks are 10 times larger than a jardine's).
You also need to put things in perspective. What the parrot eats is up to you, not him. If we left it up to them they would all end up dead from fatty liver because they would eat nothing but oil seeds. Would you allow your 2 year old to decide what his diet was going to be just so he could be 'happy''? Of course not! He would be obese and suffering from malnutrition in a matter of a couple of years.
I have transitioned over 300 birds to gloop and they all like it from the macaws to the budgies (even the canaries and cardinals love it) The only problem you have is that you did not do it gradually enough or gave it enough time. But, I warn you, when it comes to parrot keeping, nothing comes easy or quick... you try, fail, tweak, try again, fail again, retweak, try again and so on and so forth.






