How to change the default limit time?

Is there anyway to have the card - where it asks for start & end time of the event to have it automatically show up as AM Instead of PM? And have it not effect the error check routine. 

I have checked your form and it seems you have set your Time Properties  Limit time to both AM & PM. I would suggest getting the current time so that the user may update the time or not. Go to your Time Properties>Options>Default Time>Current

However, I'm not sure I understood correctly your question on error routine checking.

Can you please explain further how time affects the error check?

Looking forward for your response.

Thanks, unfortunately most events that folks enter are not for the
current time but for a date/time in the future. There are two error
routines
built into the form, one produces an error message, if the starting date is
greater than the ending date. The second one make sure that the starting
time
is less than the ending time and also checks to make that the two time
values
are different
...

It seems that the time will automatically detect if its AM or PM in your location.

If you want to show PM only, there is an option in the Limit Time for PM only.

Hope this information helps.

What I am asking is there any way for it to default to a.m. automatically
and if it evening meeting, it will allow the user to change to p.m.
...

How about the method of adding 3 time fields? The first one is hidden with a 24-hour format and set to current as the default time. 2nd time limit to AM only and the 3rd time limit to PM only. Next, show AM or PM based on the first date by conditional logic. 

Here's a demo form: https://form.jotform.com/90926930929974. 

Change the time before and after 12 to see the output.

Here are the conditions in the form:

**Note that I've shown the first time so you can change the value and see the output of the condition.