Magento2 : Change custom attribute scope not working

You've probably solved your problem, but here is solution for people coming here from google as me. I've managed it by editing it straight in database.

It's not recommended to do such things - the safest way is to delete this attribute and add it again, but sometimes you have no choice. This is e.g. how to change attribute scope to GLOBAL.

UPDATE catalog_eav_attribute SET is_global = 1, apply_to = 'simple,virtual,configurable' WHERE attribute_id = YOUR_ATTRIBUTE_ID;

And then refresh cache.

Try to run this command:

bin/magento indexer:reindex

bin/magento setup:static-content:deploy

You can save scope of custom category attribute like this using upgrade schema:

<?php

namespace Vendor\Custom\Setup;

use Magento\Catalog\Model\Category;
use Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface;
use Magento\Framework\DB\Adapter\AdapterInterface;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\SchemaSetupInterface;
use Magento\Framework\Setup\UpgradeSchemaInterface;
use Magento\Eav\Setup\EavSetup;

class UpgradeSchema implements UpgradeSchemaInterface
{
    /**
     * @var EavSetup
     */
    private $eavSetupFactory;

    /**
     * UpgradeSchema constructor.
     * @param EavSetup $eavSetupFactory
     */
    public function __construct(
        EavSetup $eavSetupFactory
    ) {
        $this->eavSetupFactory = $eavSetupFactory;
    }

    public function upgrade(SchemaSetupInterface $setup, ModuleContextInterface $context)
    {
        if (version_compare($context->getVersion(), '2.0.5', '<')) {
            $setup->startSetup();
            $this->eavSetupFactory->updateAttribute(
                Category::ENTITY,
                'custom_attribute',
                'is_global',
                ScopedAttributeInterface::SCOPE_STORE,
                null
            );
            $setup->endSetup();
        }
    }
}