Look at the 8x8 matrix - one is billed as common anode, one as common cathode - which is which? In both cases, the rows are connected to anodes, and the columns connected to cathodes.
For non-square configurations, like 5x7, you'd want to make sure the 5 anodes made up your rows (driven by the Segment pins), or the 7 anodes if wanted taller rows, with each column having a common cathode (each column driven by a digit pin).