Hi giozane,
The text with the white background in the cells has had a white background applied, whilst the other text has no background. The easiest way to fix many textboxes is with a macro:
Code:
Sub FixTextBoxText()
Dim Shp As Shape
For Each Shp In ActiveDocument.Shapes
If Shp.Type = msoTextBox Then
Shp.TextFrame.TextRange.Font.Shading.BackgroundPatternColorIndex = 0
End If
Next
End Sub