Ants live in colonies of thousands.  To control ants you need to control the colony, not the individuals, there are just too many of them.  The queen is the center of the ant colony.  She produces all the members of the colony.  Worker ants explore their surroundings for food.  When they find food, they lay down a scent trail for their friends to follow to the food source.   

To get rid of  ants in your home place a bait that the ants will eat along their scent trails (where you have been seeing them).  They will take the bait back to share with the colony.  To eliminate the ant problem worker ants must take the ant poison back  to the colony and kill the queen, otherwise there will be a continuous source of more ants.  If the ant is killed right away it doesn't carry the bait back to the colony.  There are several effective baits available.  Baits must be replaced until you don't see any more ants.  This article has additional information, including information on products, Ant Control for Householders  https://entomology.ca.uky.edu/ef619.

Boric acid can be effective.  However, you need to find a carrier that the ants like enough to eat.  A starting formula is 1/2 tsp boric acid with 1 cup of the food the ants like.  Any more concentrated and the ants won't want to eat it.  Different ants like different foods, some just like anything sweet and you can use jelly, sugar syrup or honey.  Others prefer butter, peanut butter or other foods.  Just remember the ratio:  1 cup desirable food + 1/2 tsp boric acid.  There are commercial ready-to-use baits which use boric acid as the active ingredient, like Terro.   This article has additional information on using boric acid for ants, The Truth about using Boric Acid for Ants Treatment  https://www.completehomemaker.com/boric-acid-for-ants/.

To prevent ants from getting into your home seal up all cracks and crevices in your foundation.  Keep dishes, floors and countertops clean.  Rinse containers before putting them into recycling bags.  Ant control is an ongoing process, and will have to be repeated if you find ants in your house again.