Hi there @SuzieQ!
Don here from Shopify. :)
There's not much we can say with certainty when it comes to issues like this with third-party apps, especially as it relates to your logging into your account with that app.
That said, it's always a good troubleshooting process in cases like this to ensure your browser is as up-to-date as possible and that you have cleared the cache and cookies recently.
If you're not sure how to do either or both of those, just let us know which browser you are using to access your Yotpo account and we can check for some resources on that for you.
Ultimately, your best bet for support on this issue would be to contact Yotpo themselves as they would be best equipped to provide support for their creation.
You can reach out to them using the contact details listed on their app store page or you can click on 'Get support' next to the app in your Apps menu in the Shopify admin.
All the best!