Based on user testing, we know that the both "multiple languages" and "default values (mul)" are not intuitive in the termbox.
**Termbox:**
Old:
{F42043500}
New:
{F42043514}
"default values for all languages"
**Copy of onboarding element:**
```
New! Add default labels and aliases for all languages
The default values are used for all languages with empty labels and aliases in order to minimize repetition. More information
[] Don't show this again
```
**Link target**
* Old: https://www.wikidata.org/wiki/User:Manuel_Merz_(WMDE)/Help:Default_values_for_labels_and_aliases
* New: https://www.wikidata.org/wiki/Special:MyLanguage/Help:Default_values_for_labels_and_aliases
**Acceptance criteria:**
[] The string "default values (mul)" was changed to "default values for all languages" in [[ https://codesearch.wmcloud.org/things/?q=multiple+languages&i=fosho&files=.%2A%2Fen.json#Extension:Wikibase | most of the places ]]
[] Desktop Termbox
[] Special:NewItem (T329626)
[] Special:NewProperty
[] Accessibility copy for screen readers
[] ~~Mobile Termbox~~
[] The copy of the onboarding popup was changed to the new copy.
[] The link target in the on-boarding element was changed to: https://www.wikidata.org/wiki/Special:MyLanguage/Help:Default_values_for_labels_and_aliases
**Open questions:**
* Q: Should we also rename the language code to "default" or should we keep it "mul"? (visible in the API and special pages)
** A: No, we keep the language code mul (see T345083#9199970 for arguments).