Measuring tape only giving guide lines on one axis

I am very new to sketch up - can you help me get grid lines on the the green axis
or can you direct me to a tutorial to help…many thanks

You should be able to pull guides directly off all three axes.
Also you could draw an edge parallel to the desired axis and pull a guide off the edge, meaning it also will be parallel to that axis.

p.s. sometimes it helps to shortly hover over the origin to get focus on the axes.

The tape measure does pick up a bit on the surface under it at the time. If you had a large rectangle on the ground and wanted a guide to come upwards on the blue axis, the tape measure is constantly over the green axis object, and so might stick to that.

You can tap the up arrow key to force it to go in the blue direction.

For the graphics card (for your profile) you could choose Preferences from SketchUp’s Window menu, then OpenGL, then click on the Graphic Card Details button, to see something like this: