construction lines

[pika89]

Bye to all,
excuse my tragic ignorance but I use the 3gg program:-(
However following the tutorial I found myself having to trace endless lines of construction.
I don't see them.
Can you tell me why?

 

[pilobrex]

did you press any f1-2-3-4-5?? by any chance?
you may have disabled them

 

[pika89]

I think...
I have never been seen...that is, you can't see, a black moment appears when I draw for example a curve arch and then I disappear immediately. . .