edwarzhang,
In the CLI settings page, you can type the version of your choice for Nodejs, click ‘Apply and Close’. Once done, open a new tab in the Terminal+ view and if the version you entered is not already downloaded, it will be downloaded. Once it is downloaded you will see Nodejs 8 version listed in the CLI settings. The Nodejs 8 version might have already been downloaded in the other machine, which is why you are seeing it in the list.
Hope this helps. Please let us know if you have any further questions.
–Swapna
Genuitec Support