Updating a task description without changing start date

If I change the task name also the start date is changed and I don’t want this.
Take a look of this pic

If I change the description, the task start date will be changed to 09:00 AM. In the database is saved as 09:15 and I want to keep this.

Also the time picker is in 1 hour interval. Can I have it in half an hour interval? Or an input where I can type the minutes? Documentation is here but I couldn’t find a solution


I solved using this sample

Hello Mattia,
You can also try changing the time_step option:
Here is the snippet that demonstrates how it works: