Bazen lazım oluyor:

Kaynak

 Well, the only way to go around this is a macro (!) I’ve got fromChocotooth’s blog:

Sub SetLangUS()
Dim scount, j, k, fcount
scount = ActivePresentation.Slides.Count
For j = 1 To scount
fcount = ActivePresentation.Slides(j).Shapes.Count
For k = 1 To fcount 'change all shapes:
If ActivePresentation.Slides(j).Shapes(k).HasTextFrame Then
ActivePresentation.Slides(j).Shapes(k).TextFrame _
.TextRange.LanguageID = msoLanguageIDEnglishUS
End If
Next k
fcount = ActivePresentation.Slides(j).NotesPage.Shapes.Count
For k = 1 To fcount 'change all shapes:
If ActivePresentation.Slides(j).NotesPage.Shapes(k).HasTextFrame Then
ActivePresentation.Slides(j).NotesPage.Shapes(k).TextFrame _
.TextRange.LanguageID = msoLanguageIDEnglishUS
End If
Next k
Next j
End Sub