How do I save the changes made in Nixie to my Strymon pedal?

To save changes made to the pedal in the Nixie software, just click the WRITE button.

To undo this action, click press CTRL/CMD+Z until you reach the desired place in the History pane (usually the Clean state before you clicked the WRITE button), or simply click the Clean state line item in the History pane. Then click the WRITE button.  Note that the green check mark in the History pane indicates the state that is currently saved in the device.