State tax filing

You enter state information regarding the taxability of your pension distributions largely in the federal section of TurboTax, on screens you will see after your complete the form 1099-R entries as you see here:

You may not be able to designate the pension as taxabe or not taxable in the state program, you may need to do that in the federal program. I suggest you go back and review your form 1099-R entries and approach their treatment as taxable or not on your Michigan return by looking at your entries in the federal portion of TurboTax.