From the app, you can change your profile name and your account email and password.
Open the app and tap on your profile icon in the upper left corner. Here you can edit your name and email under "edit profile' or change your password just underneath.
Open the app and tap on the three horizontal lines in the upper left corner. Then go to "Settings". Tap on "Edit profile". Here you can change your name, email and password.
If you want to change your name in a poll you have already participated in, please switch to the mobile browser or the desktop version. Then open the poll in your browser whilst being logged in to your Doodle account. Click the pencil next to your name. Change your name and save the change.