You are not supposed to amend this! 'Autoincrement' means 'give me a unique number and I do not care what it is'.
This is the server behaviour ….
However you can with SQLyog right-click a table .. ALTER TABLE .. advanced properties .. and enter the new autoincrement 'offset' before entering data. Use version 5.22 RC3 for this (some bugs were fixed in the 5.22 tree with ALTER TABLE ..advanced properties).