Projects fill in their county from the site address
The project form has a County field now, next to City, State and ZIP. Leave it blank and STrOp looks the county up from the site address after you save. A job at 3535 Factoria Blvd SE in Bellevue comes back as King.
The county matters because union agreements and prevailing-wage rate schedules both go by county. It's how STrOp picks the right wage determination for a job, and next it will pick the right labor agreement.
A county you type in is never overwritten. If the address can't be matched, the field stays blank for you to fill in by hand. STrOp never guesses the county from a ZIP code, because ZIP codes cross county lines.