We have a small family business I filed but line 20 on the Schedule K-1 shows code Z with a STMT. How can i change this? Help!

The STMT you see on your K-1 form means that there is a statement attached to it that includes the numbers that you are to enter in TurboTax for box 20. 

Code Z indicates that this is for your qualified business income (QBI) entry. You should see an amount for that on your statement, often it is the same amount as the income reported on your K-1 schedule box 1 to 3.

Enter the code Z when you enter the K-1 box 20 screen, but you don't need to enter an amount on that screen.  Continue on, and you'll eventually find the screen  "We need some more information about your 199A income or loss". 

 When you check the box next to a category on that screen, a place will open up to enter the amounts from the Statement or STMT that came with your K-1.  The applicable category (or categories) on this screen (and the following "Let's check for some uncommon adjustments" screen, if applicable) must be completed in order for your K-1 QBI information to be correctly input into TurboTax. 

Here's more discussion on K-1, Box 20, Code Z.