Hi Kalpana,
If you want to change the standard text, please follow
the steps below.
1. Run T-code： /osotr_edit
2. select text type：Short Text
3. select Language as En English
enter Alias as: CRM_IC_APPL/CATEGORY1
4. click change button
5. change the text for category1 and save your change.
Regarding category2-4, you can do the same steps as above
for Alias CRM_IC_APPL/CATEGORY2, CRM_IC_APPL/CATEGORY3 and CRM_IC_APPL/CATEGORY4.
Or you can modify the following method which I don't recommend.
CL_GSMCDDLB_DROPDOWNLIST_IMPL
METHOD / GET_CAT_LABEL_TEXT
Best Regards,
Bruce