아래 코드를 사용해주세요.

<?php if($board->isAdmin()):?>
    <?php if($board->use_category):?>
        <?php if($board->initCategory1()):?>
        <div class="kboard-attr-row">
            <label class="attr-name" for="kboard-select-category1"><?php echo __('Category', 'kboard')?>1</label>
            <div class="attr-value">
                <select id="kboard-select-category1" name="category1">
                    <option value=""><?php echo __('Category', 'kboard')?> <?php echo __('Select', 'kboard')?></option>
                    <?php while($board->hasNextCategory()):?>
                    <option value="<?php echo $board->currentCategory()?>"<?php if($content->category1 == $board->currentCategory()):?> selected="selected"<?php endif?>><?php echo $board->currentCategory()?></option>
                    <?php endwhile?>
                </select>
            </div>
        </div>
        <?php endif?>
        
        <?php if($board->initCategory2()):?>
        <div class="kboard-attr-row">
            <label class="attr-name" for="kboard-select-category2"><?php echo __('Category', 'kboard')?>2</label>
            <div class="attr-value">
                <select id="kboard-select-category2" name="category2">
                    <option value=""><?php echo __('Category', 'kboard')?> <?php echo __('Select', 'kboard')?></option>
                    <?php while($board->hasNextCategory()):?>
                    <option value="<?php echo $board->currentCategory()?>"<?php if($content->category2 == $board->currentCategory()):?> selected="selected"<?php endif?>><?php echo $board->currentCategory()?></option>
                    <?php endwhile?>
                </select>
            </div>
        </div>
        <?php endif?>
    <?php endif?>
<?php else:?>
    <input type="hidden" name="category1" value="<?php echo $content->category1?$content->category1:'접수'?>">
    <input type="hidden" name="category2" value="<?php echo $content->category2?$content->category2:''?>">
<?php endif?>

기존에 있던 카테고리 코드 부분에 굵게 표시된 코드를 추가했습니다.

관리자라면 카테고리 설정 부분이 나올 것이고, 관리자가 아니라면 카테고리가 "접수"로 등록이 될 겁니다.

FTP로 접속해서 스킨 파일 수정해보시겠어요?

<?php if($board->isAdmin()):?>
    <?php if($board->use_category):?>
        <?php if($board->initCategory1()):?>
        <div class="kboard-attr-row">
            <label class="attr-name" for="kboard-select-category1"><?php echo __('Category', 'kboard')?>1</label>
            <div class="attr-value">
                <select id="kboard-select-category1" name="category1">
                    <option value=""><?php echo __('Category', 'kboard')?> <?php echo __('Select', 'kboard')?></option>
                    <?php while($board->hasNextCategory()):?>
                    <option value="<?php echo $board->currentCategory()?>"<?php if($content->category1 == $board->currentCategory()):?> selected="selected"<?php endif?>><?php echo $board->currentCategory()?></option>
                    <?php endwhile?>
                </select>
            </div>
        </div>
        <?php endif?>
        
        <?php if($board->initCategory2()):?>
        <div class="kboard-attr-row">
            <label class="attr-name" for="kboard-select-category2"><?php echo __('Category', 'kboard')?>2</label>
            <div class="attr-value">
                <select id="kboard-select-category2" name="category2">
                    <option value=""><?php echo __('Category', 'kboard')?> <?php echo __('Select', 'kboard')?></option>
                    <?php while($board->hasNextCategory()):?>
                    <option value="<?php echo $board->currentCategory()?>"<?php if($content->category2 == $board->currentCategory()):?> selected="selected"<?php endif?>><?php echo $board->currentCategory()?></option>
                    <?php endwhile?>
                </select>
            </div>
        </div>
        <?php endif?>
    <?php endif?>
<?php else:?>
    <?php if(!$content->category1):?>
        <input type="hidden" name="category1" value="접수">
    <?php endif?>
<?php endif?>