[BirdOPrey5]

In the template: modifyprofile_birthday
near the very bottom you'll see:

$vbphrase[privacy]<br />
						<select name="showbirthday">
						<option value="0" $sbselected[0]>$vbphrase[hide_age_and_dob]</option>
						<option value="1" $sbselected[1]>$vbphrase[display_age]</option>
						<option value="3" $sbselected[3]>$vbphrase[display_day_and_month]</option>
						<option value="2" $sbselected[2]>$vbphrase[display_age_and_dob]</option>
						</select>

Change it to:

$vbphrase[privacy]<br />
						<select name="showbirthday">
						<option value="0">$vbphrase[hide_age_and_dob]</option>
						<option value="1">$vbphrase[display_age]</option>
						<option value="3" selected>$vbphrase[display_day_and_month]</option>
						<option value="2">$vbphrase[display_age_and_dob]</option>
						</select>

That will make "Show Day and Month" be selected by default each time a user modifies their profile, I'm not sure if it will do it when initially signing up but you can try- it should I would think... though on my board "Display Age and Full Date of Birth" is selected by default.

Obviously move the word 'selected' to any line you want to be the default option.