If you are attempting to change your Microsoft account password, you’ll need to sign-in to your account and change it there - then updating the corresponding stored passwords on devices as needed.
Be aware that Microsoft, in common with many other Mail providers, now use App Specific Passwords to access IMAP or POP3 mailboxes. If using Outlook or Hotmail accounts, this may be relevant to you.
The Mail App on each of your devices, such as your iPad, may require a unique App-specific password to be generated from within your Microsoft account. To do so, you’ll need to sign-in to your Microsoft account from a we-browser. Note that the system generated App Specific password will intentionally differ from your Microsoft account password - and can only be used to access your Microsoft mail.
More information about Microsoft’s App Specific Passwords can be found here:
https://support.microsoft.com/en-us/account-billing/using-app-passwords-with-apps-that-don-t-support-two-step-verification-5896ed9b-4263-e681-128a-a6f2979a7944