User blog:EliteSupreme/problem about powers and transformations

It has seen that in every new season or at least in every new transformation, the fairies lost their older transformation powers or they did not use them again as far as I've seen. And they could only use the new transformation powers even if the new powers were some of old ones with new name. Here are some examples: Bloom has had healing powers, has gotten it at  season 2 episode 10 ; Later in next seasons she never used healing power again. In season 3 the winx got their  fairy dust   ; In next seasons they never used it again but if they would they could break a lot of dark spells and heal themselves and also heal Sky and Helia instead of Krystal in season 5. I'll appreciate any help about why don't they (or can't) use older transformation powers. The winx were not able to use wings like zoomix or sub-transformations of believix.