Hi Pamm, you're best bet will be to pull them out by hand. The plants are all so close together in pots it's difficult to kill the weeds without harming the plants too. To prevent weeds this article will help - https://homeguides.sfgate.com/prevent-weeds-planters-21596.html
I have listed some videos that have step by step instructions.
Hope that helps! Good luck.
I find the best way is to pull them out by hand, then you have control!
I would consider hand pulling them. A layer of mulch might be helpful after weeding to prevent reoccurrence.
Just dig them out by hand making sure to get the root ball. Any bit up of root left will generate more weeds. Not difficult, just time consuming. I weed every day so I am not stuck all Saturday morning.