2d in 3d

i have inadvertantly, while trying to draw 2d blueprints have been drawing in 3d. in my viewport i have 2d selected and my visual style is 2d wireframe. i have been selecting lines and going to properties and changing the z axis to 0, but it only allows me to do a couple lines at a time. is there a easier way to change this z axis without affecting any other points? next question is how do i lock this as to where i cannot do this rookie mistake again?

thanks ahead to all you auto cad gurus.

Are you attempting to give all lines an elevation, in the 'Z' axis an elevation of "0"?

yes, when i started the drawing about a year ago i used a file that i already had which was also a 2d drawing, not realizing that when i select a point its not selected the z axis of zero. it will default to some random number and certain things would be drawn there and on the 0. even stranger there is a third point on the z axis that gets tossed in also. i didn't realize this till i started dimensioning things and coming up with outrageous numbers. i am dealing with it so i don't have to redraw anything, and as the particular line becomes an issue i go to properties and change the z to 0, but hoping there is an easier way.

There are a number of different ways to fix those wayward Z values.

You can select all and use the CHANGE command, PROPERTIES > ELEVATION > 0 > ENTER 2 times.

But that won't fix lines with varying Z values.

You can fix them by selecting all, then in QUICK PROPERTIES or PROPERTIES selecting LINES

and resetting the START Z and END Z values to 0.

I usually do the LINES first, then use the CHANGE command.

The FLATTEN command may also work for you.

In order to avoid future errant Z axis snaps you can set the OSNAP setting in your OPTIONS. People who are working on 2D drawings should keep this value checked.

In the image you will see circled the box which you should select.

My guess is that if you look at the older drawing in ISOMETRIC view you will see that it is either really a 3D drawing, or just badly drawn with errant Z values of its own.

You might also want to set PERSPECTIVE to 0 at your commandline.