There are three ways to edit components:
Expert Mode: This is the mode you use most of the time. Simply point at the text you want to edit, like a component value, right click, and type in the text you want. When you point at the text, the mouse cursor will turn into a text caret if you can edit it.
Assisted Mode: To enter Assisted Mode, right click on the body of the component. That will invoke a GUI that will help you edit that type of component. It's useful when you are unsure of the SPICE syntax for what you are trying to accomplish, such as entering the piecewise linear data for a current source or when you want to pick a semiconductor from a list of modeled devices.
Super Expert Mode: To enter Super Expert Mode, point at the body of a symbol, hold down the control key, and right mouse click. You can then have complete control of every attribute. You can make any attribute and string you wish and you can choose whether or not the attribute is visible from the schematic.