Hello Jonathan
Please refer to section 7.6 of the Analysis OLAP Administrator Guide.
There is a property in the mdas.properties file "multidimensional.services.prompt.dialog.show.all=false" which should be changed to true.
This will display all prompts. You will still need to do "Expand All".
The current behaviour of defaulting to "Required" only (which are expanded by default) and not showing "Optional" prompts (which are collapsed by default) is based on customer feedback and significantly simplifies the prompt dialog.
Another way of optimising prompts is to use variants (these are created within the prompt dialog). Each user can set up their own varient (or use public varients) and they can also choose one to be a default.
Regards
Ian