Why would plesk be writting these odd numbered SOA serial? Example one of mine reads:
1033924035 ; serial

If your doing it manually I would use "2002100701" as the serial as in 2002 the year 10 the month 07 the day and 01. if you make any changes to the DNS records you'll have to change the last 01 to 02 and so forth. At least this is how I learned it on my SuSE box before ever going to plesk.

dnsreport reads:
"WARNING: Your SOA serial number is: 1033924035. That is OK, but the recommended format (per RFC1912 2.2) is YYYYMMDDnn, where 'nn' is the revision. For example, if you are making the 3rd change on 02 May 2000, you would use 2000050203. This number must be incremented every time you make a DNS change.

WARNING: Your SOA REFRESH interval is : 10800 seconds. This seems a bit high. You should consider decreasing this value to about 3600-7200 seconds. RFC1912 2.2 recommends a value between 1200 to 43200 seconds (20 minutes to 12 hours; 12 hours seems very high to us), although some registrars may limit you to 10000 seconds or higher, and using DNS NOTIFY the refresh value is not as important. This value determines how often secondary/slave nameservers check with the master for updates. A value that is too high will cause DNS changes to be in limbo for a long time."

WHAT'S PLESK DOING? HOW CAN I CHANGE THESE VALUES IN PLESK FOR FUTURE SITES?