Go to your bundle editor, then open the Offers tab.
Click the small arrow to expand the offer you want to edit.
At this point, make sure not to confuse the two titles you see:
The title at the top, next to the pencil icon, is the internal offer name. It’s only for you in the admin and is never shown to customers.
The title in the “Title” field is the one that will actually be displayed on your site inside the bundle.
Edit the Title and Subtitle fields with the text you want to show on the product page.
You can also add dynamic variables (little person icon) to automatically display information such as discounted price, quantity, original price, etc.
If you run into any issues, contact MoonBundles support.