Many thanks for your detailed explanation.Hi, zorspas.
there is a main principle in the German language: the position of the verb is the second position in the sentence.
(there are some exceptions, but in our case it is on the second position.)
The default structure is subject has the first place, the verb the second:
"Du bist immer unzufrieden."
But there are a lot of possible movements.
The first place is a special place. If you move a word to the first place, you emphasize it.
If you want to emphasize "immer", you can move it there or alternatively, set the stress on it. But the verb remains in the second place. To reach this, the subject (it also may be a noun phrase) is moved behind the verb. "Unzufrieden" is part of "unzufrieden sein" where the conjugated form is: bist unzufrieden. Such a part, belonging to a verb, is usually at the very end of a sentence, if it is not moved.
You get the result:
Immer bist du unzufrieden!
This is the main idea behind.