In OIM 12c, The user search is by default comes with Display Name and Everytime you login and look for the user you have to select User Login from drop-down, to make this user search to User Login permanently follow the below mentioned steps:
1) Take the backup of the oracle.iam.ui.view.war from the OIM Server location /idm/server/apps
2) Copy the war at desktop
3) Follow the below process to make the change in the war file.
To change this functionality you will need to customize the following file where the labels are set for defining default values: iam/iam-product/consoles/Identity/ManageUsersUI/adfmsrc/oracle/iam/ui/manageusers/pages/search_usersPageDef.xml
This file which is part of adflibManageUsersUI.jar which is is located in OIM_HOME\server\apps\oracle.iam.ui.view.war
Extract the jar file ,navigate to oracle.iam.ui - manageusers - pages - search_usersPageDef.xml .
In this the following section sets the default search attribute viz "DefaultQuickSearchAttrName" :
From:
<executables>
<iterator Binds="UserVO1" RangeSize="25"
DataControl="ManageUsersAMDataControl" id="UserVO1Iterator"/>
<searchRegion Criteria="UserVOCriteria"
Customizer="oracle.jbo.uicli.binding.JUSearchBindingCustomizer"
Binds="UserVO1Iterator" id="UserVOCriteriaQuery"
InitialQueryOverridden="false"
DefaultQuickSearchAttrName="displayName"/>
</executables>
To-
<executables>
<iterator Binds="UserVO1" RangeSize="25"
DataControl="ManageUsersAMDataControl" id="UserVO1Iterator"/>
<searchRegion Criteria="UserVOCriteria"
Customizer="oracle.jbo.uicli.binding.JUSearchBindingCustomizer"
Binds="UserVO1Iterator" id="UserVOCriteriaQuery"
InitialQueryOverridden="false"
DefaultQuickSearchAttrName="userLogin"/>
</executables>
4) Save it
5) Copy the updated oracle.iam.ui.view.war in persistent volume location
6) Login to weblogic console
7) Click on deployments
8) Lock and Edit
9) Look for oracle.iam.ui.view
10) Select the checkbox and click on update
11) Click on change path
12) And select the updated war from persistent volume location which is /u01/oracle/user_projects
13) Click on Next
14) Click on Next
15) Click on Next
16) Finish
17) Click on Activate changes
18) Ignore the Error
19) Click on Activate Changes again.
20) Restart the servers.
21) Check if you see user login by default search.