Emails & Activities / Set a reminder

Hi,
I’m wondering if anybody has come accross this issue before.
When in a lead contact, I can click on the three dots on the right hand side and set a reminder. However, I’m not able to customize the time, I can only choose between the given times. Any idea on how to customize, or alter the time frames?

I don’t want to work with deadlines, this setting is ideal for what I want to use it for!

Nay help would be very mcuh appreciated.

Thanks