Find the portfolio in which you wish to alter the timezone in. On the Home tab, click the settings icon on the top right corner of the screen.
On the settings dropdown menu, select "Portfolio Settings" to proceed.
On the Portfolio Settings menu, click on the Time zone settings.
On the Time zone settings page, you will see the preset UTC time zone. A company will typically set the time zone of where they operate as it will be important to receive transaction timestamps in the correct timezone for accounting purposes. Select the Portfolio Time Zone (in UTC Offsets) bar and chose the desired time zone of operation.
After selecting the desired time zone, click the blue "Save" button and the selected time zone is now saved onto the portfolio.