Using sketch free version. the scale changes frequently. trying to get back to a usable scale that fits the screen

while in sketchup basic mode the scale switches frequently and does not fit the screen.
It appears to be in an engineering scale mode where 1" equals 150 ft. How do you get back to 1/8" = 1 ft.?

What do you mean by “basic mode”?

In SketchUp you should be modeling in real world dimensions. There is no 1/8" = 1ft scale to set in any version of SketchUp.

Scaled output would normally be done in LayOut, which is part of the SketchUp Pro package. You can do some scaled output in printing from SketchUp Free but it depends on the paper size your printer has available.

ok thank you for the reply. I will continue with that advise.

Sounds like you aren’t understanding the fundamentals of the workspace. It is a 3d environment and is basically infinite, (although it’s best kept to a reasonable size).
You usually work in real world dimensions and can zoom in and out to get close or far away. Rolling the scroll wheel of your mouse will zoom in and out. Clicking down on the scroll wheel and moving the mouse will orbit around in 3d space.