Project settings — units and sales tax
Set measurement units and sales tax once per project — they apply to every assembly in it.
Open Project Details → Project settings ("Applied to every assembly in this project").

Measurement units
Imperial (feet & inches) or Metric (meters). This drives how lengths and areas display everywhere — the status bar (Units: Imperial), the Properties panel (ft / sq ft or m / sq m), the Estimates table and exports. New projects start Imperial. Change it any time; existing measurements are converted, not re-drawn.
If saving fails you'll see "Measurement units were not saved" — retry.
Sales Tax 1 and Sales Tax 2
Two percentage fields (e.g. 8.75). They apply project-wide to every assembly and estimate line that references sales tax — set them once here rather than per line. Non-numeric input shows "{name} was not saved — enter a number".
Two fields let you model, for example, state + local tax, or material tax vs. a separate levy.
Where else settings show
The dashboard card shows Imperial / Metric next to the page count, and the status bar in the workspace shows Units.
