The biggest misconception in my experience of handling and working in the parrot industry for over 17 years is that people don't know what to feed their parrot.
Parrots on a seed based diet can develop fatty liver disease among many life threatening issues.
Parrots need to eat a well balanced pellet formulated exclusively for them. There are even pellet formulas that are designed exclusively for a particular species of parrot.
In addition to the pellets the parrot needs fruits & veggies and treats that are healthy. Human food is acceptable and they can eat most everything we eat with the exception of approx ten items that are poisonous to them however they need to be eating their own food before they can be offered ours.
The diet is of utmost importance and plays a roll in not only the health of the bird but also the temperament and and its overall well being.
Parrots need a certain amount of seed in their diet ( approx 10% ) but it should not be the diet exclusively.
Lets face it we feel better when we eat better so it is the same for a parrot.