I'm creating a form with checkboxes. When a box is clicked and the checkmark appears, I cannot click the same box to uncheck . Same thing with radio buttons. What settings am I missing to make this a simple on/ off function?

Yes! Thank you!

​@albumartist If you copied and pasted the checkbox or radio button fields, they all retained the same field name. As a result, when you select one, all of them become selected as well. 

Notice in the right-hand panel that the fields are listed as:

Check Box 1 #0
Check Box 1 #1
Check Box 1 #2
Check Box 1 #3

Since all the copied checkboxes share the same field name, Acrobat treats them as linked instances of the same field. That's why selecting one checkbox selects all of them.

Here, I am going to change the field names and tooltips for each checkbox. Double-click a checkbox to open Check Box Properties. On the General tab, change the Name field to something unique. Update the Tooltip field if desired. Repeat for each checkbox.

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Now, it should look something like this, with each checkbox having a unique name:
Check Box 1, Check Box 2, Check Box 3, Check Box 4
 

Once each checkbox has its own name, Acrobat will treat them as separate fields. Selecting Check Box 1 will no longer cause Check Box 2, 3, and 4 to be selected as well.

So, in other words, change the properties