What version of Photoshop, and are these Shape layers or raster done with a thin brush or pencil tools? Either way, you should be able to Free Transform them,, providing they are on their own layer. That would be automatic with a Shape layer, although it is possible to have multiple lines on a single Shape Layer.
The control handles can be very crowded, but if you zoom in you can drag an individual handle. The other option is having started the Free Transform process, use the fields ion the Option bar to change length width etc. One other point, if your lines are not aligned to screen edges, then the FT handles will form a box around the object which is square to the screen edge. It's usually best to create lines vertically or horizontally, do whatever edits are required, and then FT them to the final angle.