Some AMC content is in Spanish originally (for example, parts of Fear The Walking Dead). However, if you are hearing an audio track that was originally English but has been dubbed over in Spanish (or another language), then this is very likely because you have accidentally turned on your TV's secondary audio program (SAP).
This can be confusing for some people, because they will hear some content in English, but then it will switch to another language. This is because even if you have SAP turned on, not all content has a second audio track. So you will hear English, then Spanish, back and forth, even though it is all coming from the SAP track.
To fix this, check your remote control for a button marked SAP. It might be called something else on your TV, so check the audio options, or do a Google search for your TV model plus "SAP".