It is best practice to keep the original OOTB files.  First, make a copy of the current OOTB file and make changes to the copy to preserve the original OOTB file.

Service Catalog

All supported Operating Systems

1. Stop the CA Service Catalog(SC) service

2. Copy OOTB file from <USM_HOME_view_webapps_usm_path> and paste it into <file_store_custom_path> folder.

Where "<USM_HOME_view_webapps_usm_path>" stands for:
C:\Program Files\CA\Service Catalog\view\webapps\usm
and "<file_store_custom_path>" stands for:
C:\Program Files\CA\Service Catalog\filestore\custom

For example, for the LOGIN-UI: Entry number 2: Text Brand and Product Name …\view\webapps\usm\locale\icusen\logon.xml <brand> <product_name>

Copy <USM_HOME_view_webapps_usm_path>\locale\icusen\logon.xml
C:\Program Files\CA\Service Catalog\view\webapps\usm\locale\icusen\logon.xml
and paste it to 
C:\Program Files\CA\Service Catalog\filestore\custom\locale\icusen\logon.xml

Should the above folder-tree(path) not exist, create it.
So, create sub-folder 'locale' under C:\Program Files\CA\Service Catalog\filestore\custom
and create sub-folder 'icusen' under C:\Program Files\CA\Service Catalog\filestore\custom\locale
showing folder path C:\Program Files\CA\Service Catalog\filestore\custom\locale\icucen

3a. Browse into the C:\Program Files\CA\Service Catalog\filestore\custom\locale\icucen folder
3b. Open the 'filestore' file: logon.xml (with notepad) and look for "<title>CA Service Catalog</title>"
3c. Edit and Save the file from within the filestore folder tree.

Depending on the type/file that has been changed, perform the below procedure to 'clear' the Service Catalog environment:

1.  Stop the CA Service Catalog services (Accounting and Catalog).
2.  Empty/clear the %USM_HOME%\view\translets folder.
3.  Remove the %USM_HOME%\logs\*.log files.
4.  Clear the web browser cache.
5.  Start the CA Service Catalog services (Accounting and Catalog).

NOTE:  Form customizations are out of scope of Support.  This means that a future patch might override an OOTB ile which has been customized.  Therefore, after a patch has been applied, you need to check the product's 'REPLACED' folder (created during the installation of a patch), to determine whether the customized file has been included in the patch.