Memory full despite memory card?

I have a problem…

My mobile phone memory is extremely full, according to the phone are only 40MB free (…)

It is also shown to me that, for example 500 MB with pictures or 300 MB are occupied with videos, but this can't be, because they are all on my memory card.

I hope someone can help me as I can get my memory a little emptier (Huawei P8 Lite 2017)

I have little idea and also another cell phone, but try your in the setting phone, sub-column applications, then click the individual, z. WhatsApp, then go to cache and delete, you do with photos or the Google (Drive, Play Music, etc.) and the other synonymous. It works for me. Good evening