Custom Contact Me widget in the Profile Page

Generally, if you want to change things like that for an out of the box component or widget, you'll have to manually re-build it. When you do that you have full control over any format you want.

Some sample code:

<#if !user.anonymous>
	<#assign user_id = user.id/>	
	<#attempt>
		<#assign cust_date_format = settings.name.get("layout.format_pattern_date", "yyyy-MM-dd") />
		<#assign cust_time_format = settings.name.get("layout.format_pattern_time", "HH:mm") />
	<#recover>
		<#assign cust_date_format = "yyyy-MM-dd"/>
		<#assign cust_time_format = "HH:mm"/>
	</#attempt>
	<#assign query = rest("2.0", "/search?q=" + "SELECT last_visit_time FROM users WHERE id = '${user_id}'?url("UTF-8")).data.items[0] />
	<#assign last_visit_time = query.last_visit_time!"N/A" />
	Last visit time: ${last_visit_time}
</#if>