When you first create a meeting type in Appointlet, the scheduling page will default to showing available times every thirty minutes. If you would prefer to update those times you can do so with the following method.
To get started, click on the meeting type that you want to update:
From the meeting type editor, click on Availability in the left navigation menu and scroll down on the page to the section that reads Time slots will be offered every X. Click on the word Customize:
From here you can select Use a custom frequency to change the increments of the time picker on your scheduling page for this meeting type:
Once you've chosen your custom frequency, the property will be updated on your meeting type and you can hit the blue Save Changes button: