After having created your presale, regardless if it is a Standard or Fair sale, you can manage it and change some parameters. To do so, go to your presale details page and click the MANAGE PRESALE button.
Click MANAGE PRESALE
Once in the Presale Management page you can modify the time of the presale start and end, of course provided that the presale has not yet been started. You can also add your Audit & KYC certificates, manage the whitelist or modify the max buy amount.