Fix manuscript tool font issue (#1863)

Author: vkbo

novelwriter/tools/manuscript.py

@@ -836,7 +836,7 @@ def setTextFont(self, family: str, size: int) -> None:
             font = QFont()
             font.setFamily(family)
             font.setPointSize(size)
-            self.setFont(font)
+            self.document().setDefaultFont(font)
         return
 
     ##