A subdomain is a part of your Kintone URL.
For the URL "https://sample.kintone.com", "sample" is the subdomain.

The length of subdomain names must be between 3 and 32 characters.
You can use alphanumeric characters and "-" (hyphens). You cannot use a hyphen at the beginning or end of the subdomain.

You cannot use the subdomain currently in use by other customers.

It may take some time until the subdomain is changed.

1. Click the gear-shaped menu button in the header.

2. Click Users & System Administration.

3. Click Access Control.

4. Enter a new subdomain.
   

5. Click Save.

Notify users of the new URL.
If necessary, also inform users that their mobile apps need to be reconfigured and that the URL of the guest space in kintone has changed.

Kintone Users & System Administrators can change the following settings, if necessary.

• SAML Authentication
• Provisioning
• Integration with External Services

If you are using API, you need to change the destination to the new URL to send requests.
For details on API, refer to the following website:
Kintone Developer Program

If you are using plug-ins from different vendors or other integration services, change the corresponding settings as necessary.