Rule 612.2 · Text-Changing Effects
A text-changing effect changes only those words that are used in the correct way (for example, a Magic color word being used as a color word, a land type word used as a land type, or a creature type word used as a creature type). An effect that changes a color word or a subtype can’t change a card name, even if that name contains a word or a series of letters that is the same as a Magic color word, basic land type, or creature type.
Subrules
Most spells and abilities that create creature tokens use creature types to define both the creature types and the names of the tokens. A text-changing effect that affects such a spell or an object with such an ability can change these words because they’re being used as creature types, even though they’re also being used as names.