Wide Format Plotter. Plotting 1:1 with custom paper sizes.

At the company I work for we have a wide format plotter and we just received DraftSight free version. We have the custom paper size saved. When I go to use this custom paper size setting and set the size it does not stick in the print layout. We were able to do this with AutoCAD. I am wondering what I am doing wrong. Also I do not want to set up a paper size for every custom size we print. I just want to use the one option for paper size and change this in the properties. The window ends up having red boarders and does not change to specified scale and sheet size.