Jesus was talking to the 72 disciples that he sent out and gave the power to perform miracles. Those verses don't apply to us today.
(Luke 10:1 NIV) After this the Lord appointed seventy-two others and sent them two by two ahead of him to every town and place where he was about to go.
(Luke 10:9 NIV) Heal the sick who are there and tell them, 'The kingdom of God is near you.'
(Luke 10:17-20 NIV) The seventy-two returned with joy and said, "Lord, even the demons submit to us in your name." {18} He replied, "I saw Satan fall like lightning from heaven. {19} I have given you authority to trample on snakes and scorpions and to overcome all the power of the enemy; nothing will harm you. {20} However, do not rejoice that the spirits submit to you, but rejoice that your names are written in heaven."