How to change the date that defaults into Effective Thru on Bills of Materials?

The Effective Thru ( EFFT ) date is in some fields, like BOM Effective Date, Lot Effective Date,Etc...
default value is 2010/12/31, Now you can change it in DD:Century Change Year(CENTCHG). set it's default value to 30 or 40, 50. The Effective Thru Date can be to 2030/12/31,2040/12/31,2050/12/31.