==How can I test for usability issues?==
There are established standards called Heuristics that are used to evaluate the usability of a user interface design.
You can learn more about these heuristics in thsi this [https://www.nngroup.com/articles/ten-usability-heuristics/ Nielsen Norman Group article].
These 10 heuristics summarized below are a tool for discovering usability issues in a user interface.