Hi @kkpmany - please refer to this thread: Need help to replicate Year over Year - when KPI is a calculated field
It also points to the Demo Central link: https://democentral.learnquicksight.online/#Dashboard-TipsAndTricks-Calculation-Year-over-Year-KPI. If you open the analysis (edit icon in the left menu navigation) in the demo central, you can refer to the calculated fields (Prior Period, Selected Period) and how they are used with the Parameters.
Let us know if it helps. Thanks!