NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    path = [path stringByAppendingPathComponent:@"List.plist"];

    NSFileManager *fileManager = [NSFileManager defaultManager];
    if (![fileManager fileExistsAtPath:path]) {
        NSString *sourcePath = [[NSBundle mainBundle] pathForResource:CONTENT_DEFAULT ofType:PLIST];
        [fileManager copyItemAtPath:sourcePath toPath:path error:nil];
    }

    NSArray*  newContent = [[NSArray alloc]initWithContentsOfFile:path];
    NSDictionary *Dict = [[NSDictionary alloc]initWithDictionary:[newContent objectAtIndex:2]];
     [Dict setValue:@"NO" forKey:@"Enabled"];
      [Dict writeToFile:path atomically:YES];

*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<__NSDictionaryI 0x15de7ff0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key Enabled.', or Im wrong in something?

NSString *path = [[NSBundle mainBundle] pathForResource:@"List" ofType:@"plist"];

    NSString *savingPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

    NSArray*  newContent = [[NSArray alloc]initWithContentsOfFile:path];
    NSMutableDictionary *Dict = [[NSMutableDictionary alloc]initWithDictionary:[newContent objectAtIndex:2]];
    [Dict setValue:@"NO" forKey:@"Enabled"];
    savingPath = [savingPath stringByAppendingPathComponent:@"Modified.plist"];
    [Dict writeToFile:savingPath atomically:YES];

    NSLog(@"newContent:%@",newContent);
    NSArray *newnew = [[NSArray alloc]initWithContentsOfFile:savingPath];
    NSLog(@"newnew:%@",newnew);

*** Terminating app due to uncaught exception 'NSRangeException', reason: '-[__NSCFArray objectAtIndex:]: index (3) beyond bounds (2)'

NSString *path = [[NSBundle mainBundle] pathForResource:@"List" ofType:@"plist"];

NSString *savingPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
savingPath = [savingPath stringByAppendingPathComponent:@"Modified.plist"];
[Dict savingPath atomically:YES];