Cache problem

Hi i use your plugin with wprocket. I followed you instructions and add these to exclude

wmc_current_currency
wmc_current_currency_old
wmc_ip_info

i disabled session and now i get this error

[24-Apr-2020 13:50:28 UTC] PHP Warning: Cannot modify header information - headers already sent in /home/mysite/public_html/wp-content/plugins/woocommerce-multi-currency/includes/data.php on line 1351

Also at checkout i want to pay with my main currency but at tests i see that you can change currency. I made the setting at plugin but seems it doesnt work