@JeremyECrawford You said that if a spell does not say something happens it doesn't happen so with true polymorph/polymorph which says personality and alignment are retained, it doesn't mention memory. So this means a creature loses it's memories when transformed?
— Sean Stanley (@SeanPWStanley) February 7, 2018
A spell doesn't erase/suppress your memories unless the spell's text says it does.
When the text of a spell, like polymorph, says you retain your personality after a transformation, that's a terse way of saying, "You're still you, despite the radical changes you undergo." #DnD https://t.co/h6q66O5F6q
— Jeremy Crawford (@JeremyECrawford) February 8, 2018