Interesting question! 'There you go' is perhaps the most commonly used out of all the phrases. It's used when you solve a problem for someone. For example, if your computer has a problem and you come to me for help, after I fix it, I'll say, "There you go! All fixed". 'There we go' is used in a similar manner, when it's multiple people including yourself. For example, if you are on a road trip with your friends and the car breaks down, you fix it and then, you can say, "There we go! All done". 'There I go' is not commonly used. You can say that to yourself after you solve your own problem. 'Here we go' is used when you are with a group and when someone starts doing something that you want to playfully mock. For example, if one of your friends starts talking about art in front of you and other friends, you can say, "Here we go again." 'Here I go' can be used when you are starting out on an important mission. For example, if you're going to an important meeting, you calm yourself down before it and say to yourself, "Here I go." 'Here you go' is used when you are offering something to someone. For example, if your friend starts coughing all of a sudden, you offer her a glass of water saying, "Here you go. This will help you." 'There you are' is used when you have been searching for something/someone and you finally find it. For example, if I find my phone after searching for it for 10 minutes, I say, "There you are. Hiding under a pillow." 'Here you are' is used when someone shows up in front of you after a lot of struggle. For example, if a person who's been trying to avoid you for days comes to you for some help, you say, "You've been trying so hard to ignore me, but at the end of the day, here you are." Finally, you use 'Here I am' when you finally show up in front of someone/something and are openly calling it out. For example, if you finally decide to face a bully, you go up to him and you say, "Here I am. What are you going to do about it?" Hope this helps!