how to change form 941 monthly mistake to semiweekly

I filed a 941 form and checked monthly instead of semiweekly. So I need to do a 941 schedule B form but I have no idea what the exact process is required. The other information on the form was accurate, I just needed to change the depositor to semiweekly and submit a Schedule b form. There does not seem to be an exact fit for my error. Any ideas?