Costs and reports
Units, currencies and dates
Display preferences that never rewrite a record.
Where: Account menu ▸ Settings ▸ Preferences
Distances are stored in kilometres and money in minor units with the currency it was recorded in. Miles, litres or gallons, your currency and your date format are display preferences, so changing one never rewrites a record.
Mixed currencies are shown side by side and never summed at an invented rate.