If you want to update the cost/billable rate of a member, go to the 'Team' section on the sidebar, move the mouse over the certain member, click on the pen icon and edit rates.
In order to update the cost/billable rate on the level of a certain project go to the ‘Project’ section on the sidebar and change it in the edition of the project.
Updating default cost and the billable rate on the level of the whole workspace is possible in the ‘Settings’ section on the sidebar. Go there and updates rates in the ‘General Settings’ section.
It is crucial to define how cost and billable rate should be recalculated after any change. This option is located in the ‘Settings’ section on the sidebar. After the update, rates can be recalculated automatically or they can require a manual refresh.