Soundiiz is dealing with with dozens of thousands sync executions per day and multiple syncs per user.
While Soundiiz is able to do this by using APIs (technical access to music services), we are limited by APIs quotas / number of requests per second / number of requests per user.
That's why, it's technically not possible / not allowed to set yourself an hour for a sync execution. Soundiiz is automatically setting the hour depending of our servers load / API load. But you are still able to see the expected execution time on your Sync details.
However, you are free to select the frequency of your sync execution (daily, weekly, monthly). Of course, we are recommending you to set the right frequency, depending of your needs ! No need to set a "daily" frequency on a playlist which is updated once a month...
Thank you for your understanding !