I edit the "Placeholder text in the nearby app's Search Bar Feature. I enter different text in Interactivty > Search > Edit > Edit > "Placeholder" text. I can see the text update. Then when I look at the published link, the updated text disappears and is replaced with the default ESRI text.
images below and link to the site: https://arcg.is/09WTOn0
This is an issue we are working on addressing in the next update of ArcGIS Online. In the meantime, a way to work around it is to edit the Locator name in addition to the placeholder text.