Set myRange = ActiveDocument.Content
With myRange.Find
    '.ClearFormatting
    '.Replacement.ClearFormatting
    .MatchWildcards = True
    .Text = "\[*\]"
    .Replacement.Text = "[" & my(.Text) & "]" 
    .Execute Replace:=wdReplaceAll
    
End With

Private Function my(b) As String
my = b & "Q"
End Function

Sub y(yArr, N1)

Set myRange = Selection
For N =  1  To N1
With myRange.Find
    '.ClearFormatting
    '.Replacement.ClearFormatting
    .MatchWildcards = True
    .Text = "\[" & yArr(N) & "\]"
    .Replacement.Text = "[" & N & "]" 
    .Execute Replace:=wdReplaceAll
End With
Next N