My question involves employment and labor law for the state of: CA

My former employer has paid me straight time for all hours. I'm now asking the Labor Board to have them pay me OT for hours over 8/day & 40/week. Employer is disputing the OT hours as some of my clock in/out were manually inputted rather than swiped. The manual inputs are to correct missing swipes or to record times doing company errands on my way to or from work. Employer is the one that okayed any time worked. Employer is the one that would tell me to do the errands before coming in or on my way home. This was done for other employees as well as myself. Unfortunately, I'm the one responsible for manually inputting times & making any needed corrections. How do I defend myself?