Thanks for taking the time to reach out to the QuickBooks Community. I hope you're having a great day so far.
You should still see the option to search for your invoices at the top of the invoice list. You can reference my screenshot below.
If you aren't seeing this option, I recommend clearing the cache from your browser. Web browsers collect cache to save time when loading repetitive data and images. Over time these files can become outdated and corrupted, causing issues like the one with your search bar not showing. I'm including the links for all supported browsers that contain the steps to clear the cache below.