How do I change my notification email on my ipad

From: About your Apple ID email addresses - Apple Support

Add or change a rescue [for most people called a notification address] email address

1. Sign in to appleid.apple.com.

2. Select Sign-In and Security.

3. Select Rescue Email. You might be asked to answer one or more security questions or enter your Apple ID password before you continue.

4. To add a rescue email address, select Add email. Then enter your rescue email address, then select Save changes. We send a verification to that address.

5. To change a rescue email address, enter the new address. We send a verification to that address.

6. Enter the verification code and click Continue.

If at any stage you don't get an expected verification see: If you didn't receive your verification or reset email - Apple Support

Create second email address with one of the free services. It is a good idea to have multiple ways for Apple to be able to contact you should your primary method fail. People sometimes have an iCloud address as their only way for Apple to contact them but the ironic thing is, if you have a problem with your account this will cause to only way you have to contact you to help you with this to also not be accessible.

Go to settings>your name> name, phone number and email and change your mailadres there

Im assuming you mean how do I change notification settings on my iPad. Notification settings can be configured in notifications in settings.