The first thing we need to understand is if you need any of that $8k to support yourself, or if your expenses are basically covered.
1. Does your scholarship cover tuition only, or also room and board?
2. What is your living situation going to be like in college? Will you be living with your parents? In a dorm? An apartment? Who is responsible for paying your living expenses? Will you have a meal plan? How will you pay if you want to go out to eat with friends?
3. Do you have to make certain grades in order to keep your full-ride scholarship? That scholarship is likely worth a lot more than you can make at a campus job. I support you earning money, but make sure to keep your priorities in order and put your education first. My college had limits on the number of hours you could work for this reason.
3.1. Over the summer, you can probably work full time (unless also taking summer classes).
3.2. A job that gets you relevant experience is more valuable to you at this point than a job that pays more.
3.3. If your scholarship does not cover room and board, consider becoming an RA after your first year. The paycheck is terrible but at most schools it comes with free housing, which is worth more than any other job can make you.
4. On investing: keep an emergency fund in your HYSA. For most people this is 3-6 months of expenses, but that might be hard for you to calculate at this point if your expenses are quite low. I would keep a MINIMUM of $1000. You might need more if your circumstances put you at higher risk of a financial emergency, for example if you have a car you pay for yourself.
If you are new to the idea of investing, stocks and bonds, etc, start learning here:
https://jlcollinsnh.com/stock-series/After that: you didn't say what kind of Fidelity account you opened, so I'm guessing it's a normal brokerage account. You also don't say how you got $8000, but you don't have a job, so I'm inferring this is mostly gifts (???).
A great option for you to consider is opening a Roth IRA, which you can easily do online at Fidelity. There is an annual limit to contributing to an IRA, currently $7000. Plus, there is a catch that you have to have
earned income greater than the amount you put in the IRA. So, if you didn't earn your $8000 at a job, you can't use this option yet. Once you get a job, this should be the first place you invest money. If you leave your savings in a Roth IRA until retirement age, you will not have to pay any taxes on it, even though it will have grown a LOT. You can also take money back out of a Roth IRA if you need to, but there are some rules around this--avoid it if you can.
If you max out your IRA, and/or if you have savings to invest that are not
earned income, then go back to your brokerage account. You can invest in the same funds in your IRA and your brokerage account.
When I first started out, I invested in Target Date Funds. These automatically adjust your risk tolerance as you get older, so it's a good option if you are nervous about investing and don't want to have to learn the details. They do cost a little more in investment growth and sometimes in taxes. This is probably the one you would consider:
https://fundresearch.fidelity.com/mutual-funds/summary/31579B556*Note: Fidelity's target date funds are called "Fidelity Freedom" funds. There is a "Fidelity Freedom 2070" and a "Fidelity Freedom
Index 2070." You want the Index one.
Now that I know what I'm doing a little more, I've stopped investing in Target Date funds and I invest directly in this Fidelity Total Market Index Fund:
https://fundresearch.fidelity.com/mutual-funds/summary/31635T708 This costs less than Target Date Funds, and it's a good option if you are willing to put all your money in stocks. Eventually you'll need to decide what your risk tolerance is and possibly learn how to rebalance, but at your age it is not a bad idea to be 100% in stocks.
Edit to correct a detail about the second fund I suggested (it's the same one the next poster recommends).