How to understand where to file taxes when I lived and earned in different states

First you have to establish your state of residency.  Just because you are temporarily somewhere does not automatically make you a resident of that state.  

In general, you pay state taxes (if the state has taxes) to any state where you work.  In addition, you are required to report all income to your resident state.  Your resident state will give you a credit for any taxes you paid to another state on income so you are not double taxed.

See Multiple States—Where To File - TurboTax Tax Tips & Videos.

For your federal return, add up all you income from all sources in all the states and report that.

The state returns get more complicated and may depend upon which states are involved, and how much money was earned and withheld in each state.

Please respond which states are involved, and hopefully someone with knowledge of those states can advise how to handle them.  Also advise where you resided when you earned money in each state.

Thank you - I'll look at what establishes a permanent residence or address in the states where I earned - since graduating college I have lived and worked in different states.  The states where I earned and paid income tax in 2021 are; California, Nevada, Oregon, and Washington.