edit custom field

[Palver Matos Alves]

i would like to set a field required only in a spefic workflow

[Joe Pitt]

If it is a different issue type it is easy

Yes, as long as it is a different issue type. Required fields, at creation time are controlled by the field configuration scheme. That scheme is composed of one or more field configurations. Every issue type can have its own field configuration inside the field configuration scheme. If you have 5 issue types and 1 has special needs you create a field configuration for the 4 issue types and another for the 1 issue type. Then you combine them into a field configuration scheme and apply that to the project. When an issue is created, it looks for a field configuration for that issue type and uses it. If it doesn't find one it uses the default in the configuration scheme.  Copy/paste this link for more information. https://confluence.atlassian.com/adminjiracloud/configuring-a-field-configuration-scheme-844500805.html 

https://www.atlassian.com/software/jira/guides/getting-started/best-practices