In General, we can edit the text of the labels.
Sometimes, I change the value of the slope in the section label and I type it directly instead of using the expression.
This workaround is dangerous, because if I update the corridor, perhaps that value will be out of date, so I would like some command to look for all the labels which they are not using an expression , I means, they are using a manual value. Perhaps, highlight them in the drawing.
Moreover, a fast way to change all the labels which have a manual value (they were edited) to an expression again.
