This issue is caused by differences between the Language set on the part and the language set in the user's internet browser. For example, if a part has the Target language set to English (United States), users in Canada might not see the updated labels if their internet browser and other language settings are set to English (Canada). To fix this, set English (All) as the target language. See example screenshots below showing where these settings can be found

The target language is set on the part creation properties
Part creation form > Target language drop-down

The language tab specifies which specific version of a language will see the alternate text:
Donation form > Language tab

In the example shown above, the parts are set to English (United States). Users who have language settings in their internet browser or local computer set to another specific version of English, such as English (United Kingdom) or English (Australia), will not be able see the modified labels. The screenshot below shows where this setting can be found in Internet Explorer/Windows:
Internet Explorer > Tools > Internet Options > Languages