$selection->{'Find'}->ClearFormatting;
  $selection->{'Find'}->{'Style'} = $doc->Styles('Title');
  $selection->{'Find'}->{'Text'} = "app";
  $selection->{'Find'}->Execute;

  $selection->{'Find'}->{'Replacement'}->{'Text'} = "B";
  $selection->{'Find'}->Execute({Replace => wdReplaceAll});

  $selection->{'Find'}->{'Forward'} = 1; # find next instance
  $selection->{'Find'}->Execute;

  $selection->{'Find'}->{'Format'} = 1;
  $selection->{'Find'}->Execute;