$selection = $word->ActiveDocument->Content;
$selection->Find->ClearFormatting;
$selection->Find->{Style} = $word->ActiveDocument->Styles("Footnote Text");
$selection->Find->Replacement->ClearFormatting;
$selection->Find->Replacement->{Style} = $word->ActiveDocument->Styles("Footnote Text");
$selection->Find->{Text} = "Software";
$selection->Find->Replacement->{Text} = "SW";
$selection->Find->{Wrap} = wdFindContinue; 
$selection->Find->{Format} = 'True';
$selection->Find->{MatchCase} = 'False';
$selection->Find->{MatchWholeWord} = 'False';
$selection->Find->{MatchWildcards} = 'False';
$selection->Find->{MatchSoundsLike} = 'False';
$selection->Find->{MatchAllWordForms} = 'False';
$search_res = $selection->Find->Execute({Replace => wdReplaceAll});