Assuming the track is a Virtual Instrument Track, click the instrument piano keyboard button to bring up the Instrument Preset window.
This will bring up the instrument preset window filled with category presets on the left. There are four special preset categories: <Custom>, <VSTi Instruments>, <ReWire Devices> & <External Devices>.
This category will show all available virtual instruments on your computer, including any external ones. VSTis are the only supported type of plug-in. If you have a virtual synthesizer that is not showing up, you may have to edit your Plug-in folders in the Preferences.
When you click on a virtual instrument, the window will expand and you will see the following:
Click on the preset column to select a preset.
Learn more about creating your own virtual instruments.
This section will list any available ReWire applications that are available on your computer. Selecting a ReWire application will automatically create a ReWire track for that application. In the "Show Details" view, you can select instrument sources (under Presets) that are available in the ReWire application that you have selected. MIDI data from the Virtual Instrument track, or that you play live, will be routed to the ReWire application, and any audio generated by the application will appear in Mixcraft on the ReWire track.
See ReWire Tracks for more information.
This category will show all external MIDI outputs or sound card MIDI synthesizers. If you have an external synthesizer connected via a MIDI interface, select the appropriate MIDI output interface. Please note that you will not be able to render or burn the audio made by these synthesizers unless you record them to an audio track first!
Click on a category on the left and then click on a preset.
Main default categories include:
•Hits & Stabs
Click the [x] button on the top right of the window to hide the instrument dialog. Alternatively, you may click the instrument button on the track header to toggle the visible state of the instrument preset window.