Changing the management and conduct rules of your complex to force trustees to reveal detailed financial information is not the way to solve the problem.
If you are not happy with the trustees, then change them at the annual general meeting. Trustees are elected by all the owners at the AGM to represent them.
They are appointed to run the body corporate like a normal business but a managing agent will usually handle the bulk of the work. Trustees are not there to be interrogated by individual owners who want information.
The best ways to address your concerns are by raising them at the AGM, by attending a trustees’ meeting or by becoming a trustee yourself.
While the owners at the general meeting can give directions to the trustees to run the complex in a particular way, this is very seldom done.
Read the reader’s question here.