CIS (construction industry scheme) is a tax levied on contractors. Please read the HMRC guide to know if it applies to you: https://www.gov.uk/what-you-must-do-as-a-cis-subcontractor/get-paid
You can edit details on the mobile application. When you edit this information it will automatically change this information for all users (including web users)
How to edit CIS percentage:
Click the menu icon (3 horizontal lines) in the top left corner.
This will open the menu. Scroll down to company settings.
Click into your company settings. This will open the company settings page.
Click 'CIS percentage'. Edit the CIS percentage by clicking in the dialogue field and choosing from the options. Click the tick in the top right in order to save the changes.