How do i make a trigger only work for specific people?

Question

I'm trying to create a sheet where it sends an email when a check box is checked based off the information in the row of the checked checkbox. I've got everything working except it sends an email from my account regardless of who checks the checkbox. I know the user needs to give the sheet permission to use their email but when they create a new trigger that has permission to use their email the sheet sends emails from both accounts at the same time. How would I make it so the trigger that has permission to use their email is only activated when the right user checks the checkbox?