how to change meeeting capacity for one time?

Hi, @WandaSakiLee.

Don't modify that annual account... instead, subscribe to a 1-month, non-recurring add-on called Large Meetings.

First, log in to your account on the Zoom Web Portal (https://zoom.us/profile). Then go to the Zoom Pricing page (https://zoom.us/pricing) and scroll down to see the Large Meetings box:

Click the Buy Now button (don't worry, there's a few more steps before you actually buy anything!).

You will note that there are only two levels, 500 and 1,000. Any session over 1,000 attendees must be done with a Webinar, not a Meeting... but I'm guessing you don't have that big of a crowd at this point. (Some day you might!)

Assuming you just need more than 100 and less than 500, note that there are three options for you.  Click on the "Monthly (One Time)" option, and the Licenses field should update to the number 1 you see here:

When you click the blue button at the bottom of that screen, you'll see Payment information, then a Review Order Screen, and at that point, you'll confirm your purchase of a 1-month subscription of a 500-max license add-on.  This license will have to be added to your user account.

The same process applies if you decide you might need the 1,000 add-on.  Read on...

But note that if you are using registration, you can still register over 100 people before subscribing to the 500 user add-on (or the 1,000 user add-on, if your marketing efforts work out well!).  The important thing to know is that Zoom checks your maximum capacity when you start the meeting.  So if your meeting is more than a month away, for example, send out those registration requests now, see how registration is going, and be sure you don't get your one-month large-add on more than a month in advance!  I'll usually wait until a few days before the event... when you know if you'll need less than 100, or more than 500.

Hope that helps!