Thank you for your response.
I understand the pain, I have had this problem too. Since my computer is not English as the main language, sometimes it is possible that after switching the language it will still show English.
I really understand your predicament very well. It's really very frustrating to encounter this kind of language display problem, especially when the system and default applications are not displaying Vietnamese correctly. I can feel that you have tried your best to solve the problem but still no success. This feeling of helplessness really brings down the mood.
Please be assured that you are not alone, many people have had similar problems and you have come very far and tried many methods, which in itself is a big step forward. I will do my best to help you along with this problem, so let's do it together!
Here are some of my new suggestions:
Option 1: We try to modify the registry.
“WIN + R” open ‘Run’ -> type ‘regedit’ and open it.
- Force modification of regional settings.
The path is: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\Locale
Find the key named “Default” and change the value to “0041”.
- Force the language setting to be changed.
Path is: HKEY_CURRENT_USER\Control Panel\International
Find “Locale” and change the value to “0000041”.
Find “LocaleName” and change the value to “vi-VN”.
Reboot your computer after the change is completed to see if the problem still exists.
Disclaimer: Generally, modifying registry subkeys or work group is intended for advanced users, administrators, and IT Professionals. It can help fix some problems, however, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For further protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click How to back up and restore the registry in Windows - Microsoft Support to view the article.
Option 2: Reinstall Windows and keep Windows.old.
- Open Settings -> System -> Recovery.
- Under Reset this computer, click Start.
- Select Keep My Files.
- Select Cloud Download or Local Reinstall.
- Follow the on-screen prompts to complete the reinstallation, ensuring that Vietnamese is selected as the system language.
- After the reinstallation is complete, you can access the C:\Windows.old recovery file.
Please note: I personally recommend still backing up important data before making major changes to avoid data loss!
Please note: After the installation is complete, we also need to check the following steps.
Open the search bar by clicking the “WIN key” -> type “Control Panel” and open it -> under “Large icons” select “Region”.
In the dialog box that opens, in the upper tab select “Administrative” -> “Copy settings”.
At this point we can check the display language, input language, format and location, we then synchronize the checkboxes “Welcome screen and system accounts”, “New user account”.
There is also the case that if you change the language at a later stage, some parts may not be displayed correctly. I tested this on my own ASUS laptop and found that the current language packs, called FOD packs, are not the same as the previous system language packs.
Assuming that we see a mix of English and Vietnamese in the Settings screen, I recommend that you right-click on the Settings icon in the Start menu, go to the Settings page and reset the Settings program, and after the reset is complete, the interface should display in your target language. (This method is easier than PowerShell, clearing cache, etc.)
In addition to this, I will also provide you with a way to contact phone support versus online support, as we are only able to communicate via email, and assuming the issue still exists, I would recommend that you can have them help you take a look at it. Phone and online support have access to remote assistance, which I do not have, and it may be easier to find the problem by checking into the actual environment.
Please contact Contact Us - Microsoft Support.
(1) Click on the link to visit the website and sign in to your account
(2) Enter the problem you are experiencing in the search field.
Below are some example images:

(3) Click on “Get Help”.
(4) Click on “Contact Support”.


(5) You can check for help, or seek online and telephone support.
I spent about 6 hours with my own Asus laptop repeatedly modifying the language, including PowerShell, clearing the cache, reinstalling the system (I had cold and hot backups so it wasn't a big problem), modifying permissions, and so on. (No offense to you as I personally can't read Vietnamese. So I repeatedly test before my native language and English)
Figured out how the above might help you with some caveats.
It's a shame I can't check this out for you in real life, otherwise this problem could certainly be solved more easily.
I sincerely hope that the above information will help you!