If nothing works, make a text file and copy this code below and save it as php.ini
memory_limit = 64M
max_execution_time = 1000;
max_input_time = -1;
post_max_size = 20M;
upload_max_filesize = 20M;
max_input_vars = 10000;
suhosin.get.max_vars = 10000;
suhosin.post.max_vars = 10000;
Then copy this php.ini file to the root of your site and inside your admin folder, see my exemple below:
1. My path to the root of my website, where "shop.slabestesanatos.eu" must be your site: public_html/shop.slabestesanatos.eu/
2. My path for the Admin folder, where /admin771t4r1u is the custom folder that Prestashop installer creates automaticaly after installation on Prestashop, yours must be with different numbers and letters exemple: admin1234ta /shop.slabestesanatos.eu/admin771t4rt1u
This should work, if not, please let me know.