We can’t know what might be the issue without you sharing your attempt with some screenshots of your blueprints. (make sure to include all the related parts of this task, and if you’re not able to post a certain amount of images on this platform, you can include them in a video, upload it to YouTube and send it’s link 
)
Though the only thing you’d need to do would be just accessing the movement components of all of the bots, getting the max walk speed variable from the movement component and setting it’s value as you desire.
If you were already doing that however, please check if the value get’s set successfully, if so does it get reset after a short while, does the set max walk speed node even get executed at all, and include the results in your next post. You can consider using Print String nodes or breakpoints as debugging methods in your investigation. Also please explain how did you come to the conclusions you’ll state in your next post by providing the screenshots / video demonstrating your debugging process as well.