Hello there, Community!
This post explains the procedure the change the username and password of Huawei ONT's. Please see below for is details.

QUESTION
How to change the username and password of Huawei ONT's (HG8010H, HG8010Z, HG8012H, HG8040, HG8045A, HG8240, HG8245, HG8247H)?
ANSWER
Wi-Fi SSID & password
For Huawei ONTs with Wi-Fi functions, such as HG8240, HG8245, HG8045, HG8247H and HG8247, perform the following steps to change the Wi-Fi SSID and password:
1. In most cases, the default user name for logging in to the web page is root, the password is admin and the IP address is 192.168.100.1. However, for security reasons, the default password or IP address may have been changed before delivery. The nameplate prevails. Enter the IP address in the address bar of your browser.
2. Enter the default login account and password on the nameplate on the rear of the ONT and click Login.
3. Click the Advanced Configuration > WLAN tab and choose WLAN Basic Configuration from the navigation tree on the left. In the right pane, configure the basic parameters of the Wi-Fi network and modify the Wi-Fi SSID and password in the text boxes marked in red in the following figure.

4. Click Apply.
Username and password for logging in to the web interface:
For the initial username and password for logging in to the web interface of a Huawei ONT, see the device nameplate. You are advised not to change the username and password.
Huawei ONT's include:
HG8010, HG8010H, HG8010Z, HG8012H, HG8040, HG8045, HG8045A, HG8045Q, HG8110, HG8240, HG8245, HG8245A, HG8245D, HG8245H, HG8245Q, HG8245Q2, HG8245T, HG8245U, HG8247, HG8247A, HG8247H, HG8247T, HG8310M, HG8311, HG8321, HG8321R, HG8447, HG8540M, HG8546M and so on.
Related links:
https://support.huawei.com/enterprise/it/doc/EDOC1100009117
For more information about ONT:
1. How to use the WiFi SSID hiding function of an HG659
2. How to configure the DDNS on HG659
3. How to use the USB storage function of an HG659
4. How to use the WPS function of an HG659
5. How to configure the DNS server address of an HG659
6. How to troubleshoot in case of an abnormal indicator on a Huawei ONT
7. How to use the WiFi SSID hiding function of a Huawei ONT
8. How to configure the DDNS of a Huawei ONT
9. How to use the USB function of a Huawei ONT
10. How to use the WPS function of a Huawei ONT
11. How to configure the DNS server address of a Huawei ONT
12. How to configure the MAC address filtering to prevent unauthorized network access on a Huawei ONT
13. How to improve a Huawei ONT's WiFi speed
14. How to obtain user manuals for Huawei ONT
15. How to change the username and password of Huawei ONT's
16. How to change the username and password of a Huawei HG659
17. How to obtain user manuals for Huawei HG659
18. How to obtain the HG659 default IP address
19. How to specify the websites by URL filtering on Huawei ONT's
20. How to obtain Huawei ONT default IP address
21. How to reset a Huawei ONT to its default settings
Thank you for reading!
