To increase your investment, you can either cancel your investment via your portfolio and re-invest the total amount via the pitch page or pledge to invest the amount you wish to increase your investment to. If you make another investment, this will be subject to fees.
Please note your account will be suspended after your third investment attempt.
To reduce your investment, you can change your investment via your portfolio. Click on the downward arrow to the right of the pitch and you will be able to change your investment under the Transactions heading.