Here's a simple article on how to set "Leave a link to the new topic in the source forum?" for both individual and mass moving topics as by default they are both unchecked.

Two small skin edits are needed, the template names are very similar so be careful to not mix them up. , the first one is MoveTopicForm the second is MoveTopicsForm

ACP > Look / Feel > Skin Manager > (choose skin) > Manage Templates / CSS > Moderation > MoveTopicForm

Find...

<li class='field clear checkbox'>
				<input type='checkbox' id='leave_link' class='input_check' name='leave' value='y' />
				<label for='leave_link'>{$this->lang->words['leave_link']}</label>
			</li>

Change to...

<li class='field clear checkbox'>
				<input type='checkbox' checked='checked' id='leave_link' class='input_check' name='leave' value='y' />
				<label for='leave_link'>{$this->lang->words['leave_link']}</label>
			</li>

Save the change.

ACP > ACP > Look / Feel > Skin Manager > (choose skin) > Manage Templates / CSS > Moderation > MoveTopicsForm

Find...

<li class='field checkbox'>
				<input type='checkbox' id='leave_link' class='input_check' name='leave' value='y' />
				<label for='leave_link'>{$this->lang->words['leave_link']}</label>
			</li>

Change to...

<li class='field checkbox'>
				<input type='checkbox' checked='checked' id='leave_link' class='input_check' name='leave' value='y' />
				<label for='leave_link'>{$this->lang->words['leave_link']}</label>
			</li>

Again, save the change.


That's it, it should be done. Here's two quick pics although its quite obvious what its done: