How to spread 30k in HYSA as a graduate student?

So i worked through my undergrad (graduated, unemployed currently) and saved as much as i could, and now im going straight to grad school. My current splits are 30k in an HYSA with 4.5% and 10k in a personal brokerage account. I know this is more than i need in my HYSA so i’m looking to change it up. Do i put some of my savings into VOO and chill? Do i do that in a roth IRA or add to my personal account? I’m not sure if i should lock it into an IRA in case i need it to pay for parts of school or student loans after graduating. My employer during undergrad also started a 401k for me, which i have $1000 in as of now but i’m not contributing anymore, as i’m unemployed currently.