How to change the transition time of the Gullu slider. Estimated reading time: 1 minute 1,385 views You can manually adjust the slide transition time for the Gullu slider. Here are the steps to do so: – Open the file named theme.js in thegullu\assets\jsdirectory using your favorite text editor. Note: This is a custom task you perform yourself, and you carry out this process at your own risk.