Open the Kickbase app. Tap the menu icon (top left) to open the menu. Go to Settings. Select "Your Account." Tap "Edit" in the top right corner. Enter your new email address and new password. Save your changes with "Save" in the top right corner. From now on, you can log in with your new details.
If you've forgotten your password:
On the login screen, under "I already have an account. Log in now," you'll find the "Forgot password?" option. This lets you send a reset link to the email address you registered with. If the email doesn't arrive, that address probably wasn't used for your Kickbase account — try an alternative email address instead. If you're not sure which address you registered with, get in touch with support.