@Aline_Semaan,
Just set question/row with the label appearance to read_only (column) true or true() or yes. This is only an issue for Enketo (Web form). It seems fine for Collect.
As a workaround, you might either except the "bug" at the moment or use table-list structure in Enketo. (But its layout is slightly different. See XLSForm Template - Few missing Appearances - #4 by wroos)