Good day, emmaemmaemma.

Saving and filling all the vendor information when entering multiple bills is unavailable in QuickBooks Online. You'll need to re-launch a new bill once you saved the other transaction.

 I appreciate you explaining how it would help you out. Letting us know what works best for you will show our developers what they need to consider in future product updates.

While it's unavailable, I'd suggest submitting feedback within your QuickBooks Online (QBO) account. This way, it goes to our product developers to help improve your experience while using the program. Here's how. 

1. Go to the Gear icon at the upper right and select Feedback under Profile.
2. Enter your comments or product suggestions. You can also attach a screenshot or file to combine them all.
3. Click Next.
   
4. You'll be provided a list of suggested help articles related to your comments. You can read through them or choose Skip and send message.
5. Select the appropriate category from the drop-down menu.
6. Tap Send message.

You might find the following article interesting: How to set up a recurring bill. Using the recurring transactions feature, the more transactions you automate, the more time you will save by not having to create the same transactions.

Should you have follow-up concerns, please let me know. I'll be more than willing to lend you a hand. Have a good one.