Forget the HTML file and go to the source.
Open SH3Cmdr.ini located in your SH3Cmdr root folder. Look for the following:
Code:
[CAREER DETAILS]
<Commander Name>=30JUN12,"Gut Mohrberg",14,01APR34,30APR38,09JAN35,01AUG35,01FEB37,01AUG37,41,92,0
The first date is the DOB, then the POB, then the officer image index, then the promotion dates, then some numbers you need not worry about (DON'T delete them).
Change the first date but maintain the format DDMMMYY. Keep in mind though that as soon as you change the DOB you break the promotion progression dates, which SH3Cmdr calculates based on your DOB using historical Wehrmacht and Kriegsmarine rules.