Hello Anil,
I can't reproduce your stated issue.
When I set ExplorerAutoOptimizerSetting with optIn = false, then in UI, the Let AdWords automatically find new customers item of Targeting Optimization setting will be shown unchecked.
When I set ExplorerAutoOptimizerSetting with optIn = true, then in UI, the Let AdWords automatically find new customers item of Targeting Optimization setting will be checked with type Aggressive.
So I think this works as intended.
Could you please send more information like your SOAP logs, your code snippet, and ad group ID that has this problem to me by Reply privately to author?
Cheers,
Thanet, AdWords API Team