you have to override below jsp code of calendar(html\portlet\calendar) :
In init.jsp :Format df = FastDateFormatFactoryUtil.getSimpleDateFormat("dd-MMM-yyyy");in summary.jspf :<liferay-ui:calendar
month="<%= selMonth %>"
day="<%= selDay %>"
year="<%= selYear %>"
headerFormat="<%=
df %>"
data="<%= data %>"
/>
You can also refer
This Blog I tried in LR 6.1 and its working perfectly.
