Welcome to the Community space, @BethFletcher0122.

Let me share some insights concerning your client's invoices. The option to see the activity where the client viewed the invoice, is unavailable in the new invoice experience. However, you can still view the invoice activity by selecting an invoice and clicking on it once. This will display the invoicing activity on the right side of the panel.

Here is a photo for your reference:

Additionally, I recommend sending your valuable Feedback to our software engineers. This way, they can review and include your suggestions in future product updates.

Here's how:

1. Select Settings, then Feedback.
2. Enter your comments or product suggestions. 
3. Then select Next to submit Feedback.

Furthermore, you can check this article to learn how to edit your reminder message for customer invoices: Send invoice reminders automatically or manually in QuickBooks Online.

Let me know whenever you have further queries concerning viewing the invoice history. I'll be more than glad to help. Stay safe and have a great day!