KRL program content can be entered in two different ways:
handful of instructions can be inserted from the Command menu and parametrized as needed. this can be done when program is either OPEN or SELECTED. HMI checks for validity of parameters and refuses to accept command that does not meet some standard. This code entry is meant to be quick and easy, and that is what KUKA beginners start with... each line of code may look like single line but actually that is just an illusion, typical inline form instruction is actually 5-15 lines of code (or more).
the other way is to type in code without HMI assistance. That is "pure" KRL and can be entered when program is OPEN. Well... you can try to make changes this way while program is SELECT-ed but it is very unlikely that this will be fruitful. It may work on something very minor but in general this is wrong way to make changes to program that is selected. This style of code entry is meant for advanced users which is why one must login as Expert to do so. Expert user can expand the inline forms and see entire content of each instruction.