Hi Callum,
As an example if you used the FTMO app, chose the 10K account and chose the medium risk and installed the top 3 robots on an FTMO 10K Challenge or a FREE FTMO 10k demo account then you do not need to make any changes.
If you chose the medium risk robots and installed the top3 robots on an FTMO demo account or challenge then the total risk to your account will be 3%. If you want to reduce the risk to your account then you will need to adjust the lot size on each robot.
Alan,