Hi there, jacy179.
Do you recall if the app you're trying to update might've been purchased or downloaded with a different Apple ID? We're wondering this since you mentioned changing the password for her Apple ID has still resulted in the incorrect password error message. If yes, you could try that password instead to see if it may help stop that error from showing.
If the app was downloaded or purchased with her Apple ID, you could see if connecting to a different internet network may help: Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple Support As sometimes internet networks can have issues where an error may occur.
If you continue to encounter this issue, you can contact Apple Support for further assistance here: Contact Apple Support
Take care!