Can't configure estimation field

[Cindy Allwine]

Hi Guys – I am have trouble getting the estimation field to show up when creating sub tasks.   I have tried setting up estimation when configuring boards and projects, but think I am missing a major step. For example when I go to:  Board > Config > Estimation, the estimation hours field isn't available as an option (even though Atlassian documentation says it should be).

 
Also, once I do get the estimation field to display, is it possible to make it a drop down with set values (i.e 4, 8, 16 hours) instead of an open text field?

 
Thank you in advance for your help!!

[Nic Brough -Adaptavist-]

Is the "time tracking" field un-hidden in the field configuration for the project(s) in the board, and is it on the issue screens?

You can't change the system time tracking field to any other format.  Oh, and I'd strongly recommend not putting estimates on sub-tasks - although they will appear to roll up to their parent issues in plain JIRA, they don't roll up to epics or get used in Agile