How can I preserve text variables when I copy slides or text entry fields?

When you insert, copy, or duplicate a data-entry field (text or numerical), the program automatically creates a variable to store what's entered in that field. The entry is known as the variable's value. 

It sounds like you want to display the value of your username and password text-entry fields. To do that, you insert a reference to the variable within a standard text box or shape.

There are two ways to do that: 

• Type the name of the variable between percentage signs. For example: %username%
• Go to the INSERT ribbon, click Reference, and select the variable.

When you insert a variable reference, it will have yellow highlighting around it when you're editing in Storyline. That's there to make it obvious it's a reference (and not just text). The highlighting won't appear when the slide is previewed or published.

As you noted, Storyline assigns default names. I suggest you give every variable a meaningful name.