Adding additional text to Text entry field

I wouldn't make this a question slide. Instead, just insert a Text Entry field. 

When you do that, Storyline automatically creates a variable to hold the value. (I highly recommend changing the variable name to something meaningful.) It will show whatever the user types, and the user will be able to edit their text if they return to the slide. 

The tricky thing about data-entry fields is that the value isn't updated until the field loses focus. In other words, the user has to click something else to update the variable with what was entered. So you might want to include a "Confirm Your Answer" button. 

To ensure the user types something, control the Next button so it can't be used until the value of the variable ≠ [blank].

• This post might help with how to do that: TIP: Controlling the NEXT Button 101 | Articulate - Community 

I've also attached a demo file that I created earlier this year when someone asked a similar question. It show how to let the user update their entry on another slide: Insert a new Text Entry field. Change its trigger setting so it updates the same variable used in the original slide. Any change the user makes in either location will appear in the other location.

By the way, this Exchange Best Practice section is for general questions about eLearning. You’re asking how to do something in the software. That type of question is a better fit in the Discuss Articulate Products section of the website. That's where those of us who regularly answer questions about how to use the software spend more of our time. And that's where more folks go to search for answers.