Answer:
The fastest way is to edit the coordinates of several nodes at the same time. To do this, proceed as follows: Select all affected nodes (by drawing a window or by selecting them using the Ctrl key) and edit them (for example, by double-clicking one of the selected nodes). The "Edit Node" dialog box opens. The coordinates that are already uniform are specified as a value. No value is displayed in directions where the values differ. You can adjust the coordinates for all nodes at the same time.
In the example shown, you should enter the Y‑coordinate to the desired value in order to move the nodes on the line. The procedure is shown in the attached video.
If you want to divide the line by the nodes afterwards, you can use the "Connect Lines or Members" function. Thus, the line is divided into nodes and several new lines are created.
