<form action="" method="post">
    <div class="form-group">
        <label for="inputIncludeStaff">{$INCLUDE_STAFF}</label>
        <input class="js-switch" type="checkbox" name="staff"
               id="inputIncludeStaff"
               value="1"{if $INCLUDE_STAFF_VALUE eq 1} checked{/if} >
    </div>
    <div type="form-group">
        <input type="hidden" name="token" value="{$TOKEN}">
        <input type="submit" class="btn btn-primary" value="{$SUBMIT}">
    </div>
</form>
<form action="" method="post">
    <div class="form-group">
        <label for="inputIncludeStaff">{$INCLUDE_STAFF}</label>
        <input class="js-switch" type="checkbox" name="staff"
               id="inputIncludeStaff"
               value="1"{if $INCLUDE_STAFF_VALUE eq 1} checked{/if} >
        
        </br>
        
        <label for="inputShowNickname">{$SHOW_NICKNAME_INSTEAD}</label>
        <input class="js-switch" type="checkbox" name="nickname"
               id="inputShowNickname"
               value="1"{if $SHOW_NICKNAME_INSTEAD_VALUE eq 1} checked{/if} >
    </div>
    <div type="form-group">
        <input type="hidden" name="token" value="{$TOKEN}">
        <input type="submit" class="btn btn-primary" value="{$SUBMIT}">
    </div>
</form>

Add "Show nickname instead of username".
Add "Show nickname instead of username".

Add "Show nickname instead of username" option for Online Users widget.