The X & Y Axis titles on a Graph in Lt are only available to edit once there is valid data plotted. For example, if a Table you are plotting has only the Column Titles, and no numerical data, you will not be able to edit the Axis Titles. Add some 'dummy' values to your Table so data is plotted - this will allow you to access the Axis editing dialogue:
For further technical assistance with this or any other issue, please contact ADInstruments Technical Support by clicking HERE.