For QBs Desktop, this is the article that helped me. I was surprised at how DIFFICULT it was to locate this simple information. I hope it helps for online as well - I have copied the info from the article just in case it becomes unavailable as well as uploaded their screenshot.

https://support.businessasap.com/article/653-use-the-enter-key-in-quickbooks-to-move-between-fields

"Use the enter key in QuickBooks to move between fields

Question: Is there somewhere on my settings that I can select the enter key in QuickBooks to move on just using my keypad. I have to use my mouse and click on save or close?

Answer: Yes, while working in your QB file, from the top menu bar click Edit>Preferences>General tab>My Preferences and checking the box for Pressing Enter moves between fields."