Website with easy database and user friendly

Hello.

I am after some advice. I have a website that does invoicing for self employed people. It is staring to get complicated so i want to know if there is an easier and quicker way of doing this.

This is how it works at moment.

A customer signs up for an account. After i receieve the email i set them up an account.

When a user signs up their details are stored in a main database example imuser

I then set them up a personal database example im1

there pages are stored in a folder example folder user 1

So the first person to register in the main database imuser has id1, they have a personal database assigned to them im1 and when they log in they are redirected to folder user 1

The next person to register in the main database imuser has id2, they have a personal database assigned to them im2 and when they log in they are redirected to folder user 2

This is where it starts getting complicated.

Each user folder has the same pages in it but some of the pages are coded to retrieve data from their personal database.

For example in user 1 folder i have a page called income when i retrieve data to show on this page i use 2 queries on is select data from imuser where id =1 and also the other is where i use the database config for example

$servername = "localhost";
$username = "im1";
$password = "password";
$dbname = "im1";

So in user 2 folder i have same page called income when i retrieve data to show on this page i use 2 queries on is select data from imuser where id =2 and also the other is where i use the database config for example

$servername = "localhost";
$username = "im2";
$password = "password";
$dbname = "im2";

This goes on and on for each user folder.

I want to simplyfy things because each time a new user registers i have to manually set u a new folder upload all the pages and alter all the codes to suit the relevant user id which is time consuming.

Each user folder has lots of pages inside some are standarrd some have to be altered to suit new user id.

also if i have to add a new page or edit a page i then have to copy this edited page to all the user folders so that all are updated which again is time consuming.

Any advice or ideas please ?