1)go to the book icon
2)go in it and go down to family and pick that
3)go to parent
4)you click on the tama parent pic and it will go through it and then you will get a password. WRITE IT DOWN
5)go to tamatown
6)go to parent's house
7)enter password you written down
8)you meet the parent, he/she will give you a password for a souvineer
usually, you see the parent and the password in your tamagotchi when your tama is a baby or toddler. somehow, the parent and password disappears when your tama is a teenager or adult or oldie, so if you dont see the password in your parent list, it might be because of this.
hope that helped
sincerely,Tamapal3000