HOW CAN I TELL APP SCRIPT TO "GO IN THE ROW BELOW"? - google-apps-script

Question

I am a 10 years old boy. I created an app / game with google sheets that I shared with my friends: it is a kind of "virtual city", with shops (with related product catalogs and prices, to be purchased with your own virtual budget) ... but I'm going crazy trying to find the solution to this problem.
I did such a thing:
This example refers to Macdonald's. I put in the first column (players) the name of the players, in the second column (products) a validation of the data in which I insert all the macdonald's products, in the third (price) you can find the unit price of the product, in the fourth (quantity) one cell without formulas where to enter the quantity, and in the fifth (total) I put the formula: quantity x price. My problem is the BUTTON. To the "complete order" button I have assigned a macro that COPY and PASTE under all the informations of the order (for example Riccardo, salad, 5.00 € ...) and once copied it cancels them to consent to order other products.
So:
the macro I created (which script is:
function macro_vera(){
var spreadsheet = SpreadsheetApp.getActive();
spreadsheet.getRange('E12').activate();
spreadsheet.getRange('E5:I5').copyTo(spreadsheet.getActiveRange(),
SpreadsheetApp.CopyPasteType.PASTE_VALUES,false);
spreadsheet.getRange('G12').activate();
spreadsheet.getActiveRangeList().setNumberFormat('[$€-2]\\#,##0.00');
spreadsheet.getRange('I12').activate();
spreadsheet.getActiveRangeList().setNumberFormat('[$€-2]\\#,##0.00');
spreadsheet.getRange('F5').activate();
spreadsheet.getActiveRangeList().clear({contentsOnly:
true,skipFilteredRows:
true});
spreadsheet.getRange('H5').activate();
spreadsheet.getActiveRangeList().clear
({contentsOnly:true,skipFilteredRows:
true});
};
) HAS COPIED the order informations (salad ...) and PASTE it below.
But if we intend to buy, for example, three big macs that cost 10.00 each, then the total is 30.00 €, the previous informations (salad ...), when the button is pressed, will be replaced (overwritten without leaving a trace) and will be exchanged with the new ones we just added (big mac ...). I understood that the only solution is to edit the button macro script.
Can anyone tell me the commands and syntax I have to use to solve the problem?
How can I do?
thanks