In Prestashop administration, you can set up how you want your price to be displayed. You have five possibilities (the X corresponds to the currency's symbol):

But what if these five are not enough?  You will have to change the core function displayPrice. We will do it via override, on following example where I was asked by client from Spain, how to be able to use price format 1.000,00 €.

Option 4 – 0,000.00X is already close to this request, it’s only using opposite delimiters. We will change this via override:

1. Create new file Tools.php in folder override/classes/ and inside php tags, start with usuall override code

class Tools extends ToolsCore { } 

2. Inside the override, paste the original function displayPrice from classes/Tools.php

3. in this function, change this

case 4: 
$ret = number_format($price, $c_decimals, '.', ',').$blank.$c_char;


case 4:
$ret = number_format($price, $c_decimals, ',', '.').$blank.$c_char;

This will modify the option number 4 in select list to switch dot and comma, so instead of 1,000.00 €, the prices will be formatted like 1.000,00 €