I changed the logo, but the previous one was still showing up when I previewed the invoice. I would appreciate help me with this?Thank you.

Hi there, 

Welcome to the QuickBooks Community. It's great to learn you're customizing your invoices in QuickBooks so they stand out to your clients. Rest assured, I'll be happy to share more info so you can send your invoices with confidence and get paid with ease. 

After customizing a custom form style (invoice) in QuickBooks, it's important to note that the new changes take effect on new invoices that you create. The invoices that existed before changing the logo will still show the old logo when you preview them, however, when the customer receives the invoice, they'll be able to see the new logo. The logo won't show on the preview of the invoices that existed before making the logo change. You can try this out on your end by sending the invoice to your email instead of the client's email so you can see what the invoice will look like with your new logo.

Let me know if this info here helps. I'll be one message away in case you have other questions or if you need further assistance. Otherwise, I wish you a great rest of the day.