How to check what proxy is being used?

I'm curious, how exactly can one check what proxy is being used on their system or device? Is there a specific step-by-step process or a software tool that one can utilize to gain insight into the proxy configuration? And moreover, why is it important to keep track of the proxy being used, particularly in the realm of cryptocurrency and finance? Understanding these nuances can be crucial for maintaining security and ensuring a seamless digital experience.