An Access application option Move After Enter exists, with three alternatives:

• Don't move (allows more specific programming in a KeyDown event procedure)
• Move to the next control (the default, behaves as does Tab)
• Move to the next record (more intuitive for many, and saves the record)

These can be set programmatically but it's easiest to go to Access Options > Advanced > Editing and tick the appropriate button. This option applies application-wide.

TextBox.EnterKeyBehavior has two options, Default and "New Line In Field". The latter overrides the application-wide Access option for that text box, and doubtless is the better choice for any multi-line text box.

Better to trigger the Submit button otherwise. Clicking on it is always an option. If it follows the text box in the tab order, then tabbing from the text box will highlight it and then, pressing Enter will trigger it.