Use: To change the fill color , border color , etc of all textboxes (shapes) on active sheet

Sub format_all_textboxes_using_vba()
Dim shp As Shape

For Each shp In ActiveSheet.Shapes
If shp.Type = msoTextBox Then ' choose shape
shp.Fill.ForeColor.RGB = RGB(255, 255, 204) ' choose fill color
shp.Line.Weight = 1 ' adjust width
shp.Line.ForeColor.RGB = RGB(255, 0, 18) ' choose color
shp.Line.DashStyle = msoLineSolid ' choose style
End If
Next

End Sub