Tonsak Jaruputhikorn

This is actually by design because the enter key does more things across the application.  However, you have two ways to solve this:

1. use the SDLX user profile which I believe does this by default:
   
   
   
2. or manually edit your usersettings.xml as explained in this KB article:
   gateway.sdl.com/.../communityknowledge

For option 2, can I added two shortcut keys i.e. Ctrl + Enter and Enter + Ctrl for a purpose of confirming segments and move to the next one in this case?

I tried to add the shortcuts and it does not seem working per that article. As this is for version 2019 and the article is for previous versions. 

Tonsak Jaruputhikorn said:

this is for version 2019 and the article is for previous version

It does not matter. The profile management feature works the same way in Trados 2019.
However, you just can't use the "Enter+anything" combination because it means that you press Enter first and only then "anything" else. It does not work this way. When you press and hold Ctrl first, nothing happens because your computer "knows" that the Ctrl key is mainly used with other keys, and it waits for you to press a second key. Even if the Ctrl key is used alone, you have to release it before it works. This is how command keys work (Shift, Ctrl and Alt).
On the other hand, the Enter key executes its function as soon as your press it without waiting. You don't even need to release the Enter key for it to execute a command. That is why Enter+key is not possible neither with Trados, nor with any other app. Even with the SDLX profile, it is Enter alone that confirms segments, but not Enter+Ctrl.

Tonsak Jaruputhikorn said:

this is for version 2019 and the article is for previous version

It does not matter. The profile management feature works the same way in Trados 2019.
However, you just can't use the "Enter+anything" combination because it means that you press Enter first and only then "anything" else. It does not work this way. When you press and hold Ctrl first, nothing happens because your computer "knows" that the Ctrl key is mainly used with other keys, and it waits for you to press a second key. Even if the Ctrl key is used alone, you have to release it before it works. This is how command keys work (Shift, Ctrl and Alt).
On the other hand, the Enter key executes its function as soon as your press it without waiting. You don't even need to release the Enter key for it to execute a command. That is why Enter+key is not possible neither with Trados, nor with any other app. Even with the SDLX profile, it is Enter alone that confirms segments, but not Enter+Ctrl.

Thank you, Steven. That's clear.

However, in the user settings, can I type Enter instead of Return? Because in 2019 version, they used the word: Return.

You have to create a custom shortcut first. In Trados, go to Options>Shortcuts and assign Ctrl+Alt+Space (for example) to the command that is executed with Ctrl+Enter by default (Confirm and Move to Next Unconfirmed Segment).
Then close Trados and go to C:\Users\[YOUR USER NAME]\AppData\Roaming\SDL\SDL Trados Studio\Studio16 to open UserSettings.xml with Notepad. Find ConfirmAndMoveToNextUnconfirmedSegmentAction, remove "Control, Alt, Space" and type "Enter" instead. Save and close the file. Open Trados. Go  to Options>Shortcuts again to check if there is Enter alone assigned to "Confirm and Move to Next Unconfirmed Segment".
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However I still recommend that you use the default shortcut (Ctrl+Enter). Firstly, it is commonly used in many other CAT tools, and secondly, it may cause conflicts because pressing Enter alone may execute some other commands (I am not sure about it, but be careful not to execute Quit without saving instead of Confirm).
UPD: Ah, you version is 2019... Ok, sorry for misreading. However I can't see the word Return either in the article, or in Trados 2019 shortcuts screenshots. The foregoing is valid for 2019 too.
UPD2: Ok, now I understand why you see Return. Before posting this comment, I tried it myself (to make sure it works fine) and I assigned Enter by editing the xml file. Then I had to return to my work and re-assigned Ctrl+Enter through Options. Once I did it, there appeared the word Return in the xml file instead of Enter, weirdly, even though it was Enter before all those manipulations. But they seem to be interchangeable. You can equally use Return and Enter to the same effect.