arielleC

Problem:
Want to have a custom slug appear in the URL instead of current language code.

Solution:
0. Make a full backup of the site.
1. Edit the existing language with the undesired slug (example: pt-pt).
2. Change its default locale from the current one (example: pt_PT) to any other, such as pt_XX.
3. Now add your custom language with the desided code for example "pt" - the URL will then be http://www.site.com/pt/
4. Also set the default locale of the new language to the one from the old language (pt_PT).

Relevant Documentation:
https://wpml.org/forums/topic/change-english-language-code-to-en-us/#post-6148751