To adjust volume overlay histogram colours
1. Click on "Settings" This can be found in left bottom of Fcharts screen
2. Thereafter click on "Indicator Setup"
3. Thereafter clickon "Colours"
4. In the dropdown box select "Volume Overlay"
5. Box below that dropdown box shows the colour. Click on that box. "COlour Picker" box will openup. Select whatever colour you want click O. K. to close that window. Thereafter click apply. That is it
Hope this helps