why input value doesn't change while function fires

I am coding a unit converter and its job is to convert a given amount of seconds to what ever unit the user whichs. the convertion system works perfectly but here comes the problem: the value of input doesn't change as user type their number in it. I don't see what the problem is.

HTML:

<body>
    <select class="select">
        <option value="second">second</option>
        <option value="minute">minute</option>
        <option value="hour">hour</option>
        <option value="day">day</option>
    </select>
    <input class="inp" type="text">
    <p class="p"></p>
    <script src="Untitled-1.js"></script>
</body>

JS:

let select = document.querySelector(".select")
let userAmountInput = document.querySelector(".inp")
let p = document.querySelector(".p")

let array = [
    {
    name:"second",
    second: userAmountInput.value * 1,
    minute: userAmountInput.value / 60,
    hour: userAmountInput.value / 3600,
    day: userAmountInput.value / 86400,
},
            ]

function updateP(e) {
    if (e.key == "Enter") {
        let x = select.value
        p.innerHTML = array[0][x]
        console.log(array[0][x])
    }
}
userAmountInput.addEventListener("keyup",updateP)

Solution

select.value doesn't hold the value, you should use the event: event.target.value
The array makes no sense, lets change that:
1. To an object containing functions
2. Get the function for the selected type
3. Call the function with the current input value

let select = document.querySelector(".select")
let userAmountInput = document.querySelector(".inp")
let p = document.querySelector(".p")

const converters = {
    second: (n) => n * 1,
    minute: (n) => n / 60,
    hour:   (n) => n / 3600,
    day:    (n) => n / 86400
};

function updateP(e) {
    if (e.key == "Enter") {
    
        if (!converters[select.value]) {
            console.error('No converter found for', select.value);
            return;
        }
        
        let x = +e.target.value;
        let y = converters[select.value];
        p.innerHTML = y(x);
    }
}
userAmountInput.addEventListener("keyup",updateP)

<body>
    <select class="select">
        <option value="second">second</option>
        <option value="minute">minute</option>
        <option value="hour">hour</option>
        <option value="day">day</option>
    </select>
    <input class="inp" type="text">
    <p class="p"></p>
    <script src="Untitled-1.js"></script>
</body>