Suena absurdo, pero PowerPoint no permite cambiar el idioma de todos los cuadros de texto de todas las diapositivas de una presentación. Así que si por ejemplo, partimos de un archivo que contiene una presentación en inglés, que queremos traducir al castellano, tendremos que ir recorriendo cada uno de los cuadros de texto, y cambiando su idioma, para que el corrector ortográfico no nos marque su contenido como incorrecto.

La solución es usar una macro VBA, que haga justamente eso. Por suerte para nosotros, lo podemos hacer con mucha facilidad.

1) Cogemos el código de la macro siguiente y pulsamos CTRL-C (Copiar):

Option Explicit
Sub CambiarIdioma()
    Dim oSlide As Slide
    Dim oShape As Shape
    Dim sLocale As String
 
    sLocale = InputBox("Introduce el idioma de destino:" & vbCrLf & "- 1033: Inglés (Estados Unidos)" & vbCrLf & "- 3082: Español (Internacional)" & vbCrLf & vbCrLf & "Más en: http://msdn.microsoft.com/es-es/goglobal/bb964664.aspx", "Idioma", "1033")
    For Each oSlide In ActivePresentation.Slides
        For Each oShape In oSlide.Shapes
            If ((oShape.Type = msoTextBox) Or (oShape.Type = msoPlaceholder)) And oShape.HasTextFrame Then
                oShape.TextFrame.TextRange.LanguageID = sLocale
            End If
        Next
    Next
End Sub

2) Pulsamos ALT-F11 (Editor de Visual Basic for Applications).
3) Vamos a Insertar -> Módulo
4) Pulsamos CTRL-V (Pegar) con el código
5) Pulsamos F5 (Ejecutar)
6) Escogemos la marco CambiarIdioma y pulsamos el botón de Ejecutar
7) Cuando nos pregunte el idioma que queremos usar, introducimos su LCID en base a la siguiente tabla:

IdiomaLCID
Afrikaans – South Africa1078
Albanian – Albania1052
Alsatian1156
Amharic – Ethiopia1118
Arabic – Saudi Arabia1025
Arabic – Algeria5121
Arabic – Bahrain15361
Arabic – Egypt3073
Arabic – Iraq2049
Arabic – Jordan11265
Arabic – Kuwait13313
Arabic – Lebanon12289
Arabic – Libya4097
Arabic – Morocco6145
Arabic – Oman8193
Arabic – Qatar16385
Arabic – Syria10241
Arabic – Tunisia7169
Arabic – U.A.E.14337
Arabic – Yemen9217
Armenian – Armenia1067
Assamese1101
Azeri (Cyrillic)2092
Azeri (Latin)1068
Bashkir1133
Basque1069
Belarusian1059
Bengali (India)1093
Bengali (Bangladesh)2117
Bosnian (Bosnia/Herzegovina)5146
Breton1150
Bulgarian1026
Burmese1109
Catalan1027
Cherokee – United States1116
Chinese – People’s Republic of China2052
Chinese – Singapore4100
Chinese – Taiwan1028
Chinese – Hong Kong SAR3076
Chinese – Macao SAR5124
Corsican1155
Croatian1050
Croatian (Bosnia/Herzegovina)4122
Czech1029
Danish1030
Dari1164
Divehi1125
Dutch – Netherlands1043
Dutch – Belgium2067
Edo1126
English – United States1033
English – United Kingdom2057
English – Australia3081
English – Belize10249
English – Canada4105
English – Caribbean9225
English – Hong Kong SAR15369
English – India16393
English – Indonesia14345
English – Ireland6153
English – Jamaica8201
English – Malaysia17417
English – New Zealand5129
English – Philippines13321
English – Singapore18441
English – South Africa7177
English – Trinidad11273
English – Zimbabwe12297
Estonian1061
Faroese1080
Farsi1065
Filipino1124
Finnish1035
French – France1036
French – Belgium2060
French – Cameroon11276
French – Canada3084
French – Democratic Rep. of Congo9228
French – Cote d’Ivoire12300
French – Haiti15372
French – Luxembourg5132
French – Mali13324
French – Monaco6156
French – Morocco14348
French – North Africa58380
French – Reunion8204
French – Senegal10252
French – Switzerland4108
French – West Indies7180
Frisian – Netherlands1122
Fulfulde – Nigeria1127
FYRO Macedonian1071
Galician1110
Georgian1079
German – Germany1031
German – Austria3079
German – Liechtenstein5127
German – Luxembourg4103
German – Switzerland2055
Greek1032
Greenlandic1135
Guarani – Paraguay1140
Gujarati1095
Hausa – Nigeria1128
Hawaiian – United States1141
Hebrew1037
Hindi1081
Hungarian1038
Ibibio – Nigeria1129
Icelandic1039
Igbo – Nigeria1136
Indonesian1057
Inuktitut1117
Irish2108
Italian – Italy1040
Italian – Switzerland2064
Japanese1041
K’iche1158
Kannada1099
Kanuri – Nigeria1137
Kashmiri2144
Kashmiri (Arabic)1120
Kazakh1087
Khmer1107
Kinyarwanda1159
Konkani1111
Korean1042
Kyrgyz (Cyrillic)1088
Lao1108
Latin1142
Latvian1062
Lithuanian1063
Luxembourgish1134
Malay – Malaysia1086
Malay – Brunei Darussalam2110
Malayalam1100
Maltese1082
Manipuri1112
Maori – New Zealand1153
Mapudungun1146
Marathi1102
Mohawk1148
Mongolian (Cyrillic)1104
Mongolian (Mongolian)2128
Nepali1121
Nepali – India2145
Norwegian (Bokmål)1044
Norwegian (Nynorsk)2068
Occitan1154
Oriya1096
Oromo1138
Papiamentu1145
Pashto1123
Polish1045
Portuguese – Brazil1046
Portuguese – Portugal2070
Punjabi1094
Punjabi (Pakistan)2118
Quecha – Bolivia1131
Quecha – Ecuador2155
Quecha – Peru3179
Rhaeto-Romanic1047
Romanian1048
Romanian – Moldava2072
Russian1049
Russian – Moldava2073
Sami (Lappish)1083
Sanskrit1103
Scottish Gaelic1084
Sepedi1132
Serbian (Cyrillic)3098
Serbian (Latin)2074
Sindhi – India1113
Sindhi – Pakistan2137
Sinhalese – Sri Lanka1115
Slovak1051
Slovenian1060
Somali1143
Sorbian1070
Spanish – Spain (Modern Sort)3082
Spanish – Spain (Traditional Sort)1034
Spanish – Argentina11274
Spanish – Bolivia16394
Spanish – Chile13322
Spanish – Colombia9226
Spanish – Costa Rica5130
Spanish – Dominican Republic7178
Spanish – Ecuador12298
Spanish – El Salvador17418
Spanish – Guatemala4106
Spanish – Honduras18442
Spanish – Latin America22538
Spanish – Mexico2058
Spanish – Nicaragua19466
Spanish – Panama6154
Spanish – Paraguay15370
Spanish – Peru10250
Spanish – Puerto Rico20490
Spanish – United States21514
Spanish – Uruguay14346
Spanish – Venezuela8202
Sutu1072
Swahili1089
Swedish1053
Swedish – Finland2077
Syriac1114
Tajik1064
Tamazight (Arabic)1119
Tamazight (Latin)2143
Tamil1097
Tatar1092
Telugu1098
Thai1054
Tibetan – Bhutan2129
Tibetan – People’s Republic of China1105
Tigrigna – Eritrea2163
Tigrigna – Ethiopia1139
Tsonga1073
Tswana1074
Turkish1055
Turkmen1090
Uighur – China1152
Ukrainian1058
Urdu1056
Urdu – India2080
Uzbek (Cyrillic)2115
Uzbek (Latin)1091
Venda1075
Vietnamese1066
Welsh1106
Wolof1160
Xhosa1076
Yakut1157
Yi1144
Yiddish1085
Yoruba1130
Zulu1077
HID (Human Interface Device)1279

Si nos hemos equivocado, volvemos al paso 5), volviendo a ejecutar la macro, con el nuevo idioma.