Based on code from
Finding and replacing symbols the following will replace the alpha and beta characters with Times New Roman font. The font size is set to 14 so you can easily see that the font has been replaced. If that works for you delete the two font size lines. You can add any other Greek characters to the array as required.
Code:
Sub Macro1()
Dim vFindText As Variant
Dim i As Integer
vFindText = Array(ChrW(-3999), ChrW(-3998))
For i = 0 To UBound(vFindText)
Call FindSymbols(FindChar:=CStr(vFindText(i)), FindFont:="Symbol")
Next i
End Sub
Sub FindSymbols(FindChar As String, FindFont As String)
Dim FoundFont As String, OriginalRange As Range, strFound As Boolean
Application.ScreenUpdating = False
Set OriginalRange = Selection.Range
strFound = False
With Selection.Find
.ClearFormatting
.Replacement.ClearFormatting
.Text = FindChar
.Replacement.Text = ""
.Forward = True
.Wrap = wdFindStop
.Format = False
.MatchCase = False
.MatchWholeWord = False
.MatchWildcards = False
.MatchSoundsLike = False
.MatchAllWordForms = False
Do While .Execute 'Keep going until nothing found
If Dialogs(wdDialogInsertSymbol).Font = FindFont Then
strFound = True
Selection.Font.Name = "Times New Roman"
Selection.Font.Size = 14
Else
Selection.Collapse 0
End If
strFound = False
Loop
If Not strFound Then
'if nothing found, search from the beginning of the document
ActiveDocument.Range(0, 0).Select
Do While .Execute
If Dialogs(wdDialogInsertSymbol).Font = FindFont Then
Selection.Font.Name = "Times New Roman"
Selection.Font.Size = 14
strFound = True
Else
Selection.Collapse 0
End If
strFound = False
Loop
End If
End With
OriginalRange.Select
Set OriginalRange = Nothing
Application.ScreenUpdating = True
End Sub