alt+F11，打开宏编辑器运行如下代码：
Sub AAA()
Dim R As Range, L As Long, S As String
Application.ScreenUpdating = False
S = "红" ‘要标记的字符
L = Len(S)
For Each R In Selection
If InStr(R, S) > 0 Then R.Characters(InStr(R, S), L).Font.Color = vbRed
Next
Application.ScreenUpdating = True
End Sub
原文：https://www.cnblogs.com/goding/p/10400037.html