how to input a 5/5 ARM (30 year amortization) into APRWIN correctly?
The first step is to ignore the payment information that Section 1026.18(s) requires you to disclose. This is not the payment schedule. The APR, FC, payment schedule, and TOP are all based on the payment schedule that Section 1026.18(g) would require you to calculate and disclose.
Your loan documentation system should generate an 18(g) payment schedule in order to comply with the record retention requirements of Section 1026.25. Assuming an 18(g) schedule is somewhere in your records, you simply confirm its accuracy. Official Interpretations 8 and 10 under Section 1026.17(c)(1) tell you how to do this.
After you have verified the 18(g) payment streams, load them into APRWIN and you will confirm a properly calculated APR.