If a rule exists at both global and project level, which one applies?
The rules set at the project level always take precedence. If a project rule has a corresponding rule in the Settings screen, any change to the rule at the global level does not affect existing projects. It only affects new projects and they inherit all the project rules set at the global level by default. However, the project-level rule will again take precedence. Check out this article for more: Global and project-level rules.