Every time I see tutorials of people using line tools it goes diagonal but for me to either goes side to side or up and down. I don’t know why this is happening
Click the “Ortho” control to toggle it off.
In your case, the
Ortho control is already off.
If you are holding the Shift key when drawing the line, make sure that the
Ortho snap every x degrees setting in the Rhino Options → Modeling Aids is set to 45 degrees.