Frustrated that you put the penguin glyph in and still keep getting the Pig? It all has to do with macros, and here's how to fix it.

When you do "/cast Polymorph" in a macro, it casts the highest rank of the spell. The game now considers Polymorph (Pig) to be the highest rank of polymorph available, so it casts that. Well unfortunately, Pig does not benefit from the Penguin glyph, so you still get your little squealer.

The solution is to force the game to use polymorph rank 4 by doing this:
/cast Polymorph(Rank 4)

You can shortcut this by opening your spell book along with your macros and shift-clicking the rank 4 polymorph. This will paste it into the macro.

If Rank 4 doesn't show up in your spell book, uncheck the "Hide Lower Ranks" checkbox on the top of the spell book.