First, you should use different proxy or vpn connections when you log in to those accounts. I recommend 3-5 accounts per proxy (it worked well for me, maybe others would suggest less).
Second: they can detect not just your IP address (what you can hide with proxies), they are also able to detect the unique ID of your devices. So when it's not crucial, I log in to my accounts from an incognito window in Chrome (with proxy). It's harder to track a browser than the Instagram app on your mobile.