When you're connected to the host computer, you can change the resolution of the video stream. This change will take effect immediately, and you can make the change on the host settings page. Please note, however, that you must be the owner of the hosting computer (i.e. you're signed in on the host computer) for the changes to override the default resolution of the hosting computer.
If your hosting computer does not support the resolution that you're requesting based on Windows Display Settings, Parsec will switch to the closest resolution available. To add a resolution to your hosting computer, please add that resolution via Windows Display Settings or the AMD/Nvidia control panel.
If the resolution you want to switch to is not listed in Parsec, you can use this advanced setting.