Possible causes are as follows.

• You did not click Update App after changing the app settings.
• The Localization setting in the App Settings tab on the "App Settings" screen is configured.

Following are the solutions for each of the situation.

If the Update App button at the upper right of the "App Settings" screen is clickable (if the button is blue), the setting changes are not yet applied to the app.
Click Update App, and then click Update App on the confirmation dialog to apply the setting changes to the app.

If the Localization setting is configured, the app name and the field names specified for a user's language in the Localization setting take precedence.
On the "App Settings" screen, select the App Settings tab, select Advanced Settings and then Localization, and check the setting.
If you have changed anything, click Save. After that, click Update App, and then click Update App on the confirmation dialog.