Why are Closed/Resolved issues displayed as OPen on Customers list?

[First Line]

Why are Closed/Resolved issues displayed as OPen on Customers list?

[Niclas Sandstroem]

Check how its mapped.

https://confluence.atlassian.com/servicedeskcloud/configuring-request-types-and-workflows-732528910.html#Configuringrequesttypesandworkflows-CustomizingWorkflowCustomizetheworkflowstatusesforarequesttype

Do you set a resolution when the issue is closed/resolved?

[First Line]

There is a resolution field when looking at the issue outside of 'edit mode'. However if you click 'edit' the Resolution field doesn't display. How do I remove the resolution field? We won't need it as we'll let the customer know what the resolution is by using comments. 

[Niclas Sandstroem]

You should not remove the resolution field. https://confluence.atlassian.com/adminjiracloud/defining-resolution-field-values-776636351.html

[Nic Brough -Adaptavist-]

You do not.  JIRA uses the resolution field as an open/closed indicator.  You can automate it completely, by setting/clearing it in post-functions in your workflows, but you can not just remove it.  If you don't set it, the issue is open.