How can i resize sprites within a sheet?

I want to make a sprite animation however when i used the sprite unpacker (alfred) and export them into a folder and use them in adobe flash,i have to resize them and i end up getting the sizes wrong despite them being aligned.I tried the option where it'll automatcially resize the sprites to make them look the same but that didnt work meaning it didnt work AT ALL.

So i was wondering how can i resize sprites within a sheet so i dont have to resize each frame.