Jesus told his disciples, in this world you'll have trouble, but take heart, I have overcome the world. John 16:33 Jesus demonstrated his authority and his power over every work of the devil. And he gave us the authority to release his power the same way he did as led by the Holy Spirit and through faith in God's word.
Speak to your mountain. Mark 11:23 Truly, I tell you, if anyone says to this mountain, go throw yourself into the sea, and does not doubt in their heart, but believes that what they say will happen, it will be done for them. How can you have faith that a promise is God's will for your situation?
Romans 10:17 so then comes by hearing and hearing by the word of God. Word in the original Greek is rhema. This is not graphe, which is the word typically used to mean scripture or Logos, which our Bibles also translate as word. Rhema means the spoken word. Faith comes from what God speaks to us.
It really is true that one word from God changes everything. Speak to your mountain. See Mark 11:23. First, look up verses that say what God says about your problem. Second, let Holy Spirit quicken God's word. Let him speak to you through those scriptures. Once you have a promise from him, then the third step is to pray, declare and thank God for His promise until it comes to pass in your life.