Comments can be enabled or disabled on a per post basis, and post before the settings change will have them enabled.

To change this in SchoolPress/WordPress you need to navigate to:

To edit a Post individually:

1. Posts
2. Click Edit on the Post you would like to disable this for
3. Click Screen Options at the top right corner of the screen
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4. Select "Discussion"
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5. Scroll down the page to the Discussion area and uncheck allow comments
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To Edit Posts in Bulk:

Navigate to Posts
  1. Click the checkbox next to the Title Header for Select all (or select the boxes next to the Titles of the blogs you would like to edit)
  2. Click the bulk Actions Checkbox and select Edit, then Apply
  3. From here you can bulk edit all the blogs at once by clicking where it says Comments and selecting Do Not Allow
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