When editing anything in Moodle be sure to 'Turn Editing On'. Moving items in sections of Moodle once editing is turn on is pretty easy. Look for the four directional arrow. Once you've selected the item you can drag and drop within the course tab.
Moving across tabs is a bit different.
This alters the icon from being a four directional arrow to a two directional arrow, which allows you to move content cross-sectionally.
You can now arrange content across various tabs. Simply select the content you wish to move and its chosen tab and drop it to the desired space provided.
If you want to move 'Topic 10' to be after 'Topic 1' then click 'Topic 1' in the list.