Replace place_order text button

in 1.3.1 you can change the wording further by adding this to functions.php

//your own proceed to checkout text
add_filter('gpls_woo_rfq_proceed_to_checkout','gpls_woo_rfq_proceed_to_checkout',10,1);

function gpls_woo_rfq_proceed_to_checkout($proceed_to_checkout){

	$proceed_to_checkout = "your own proceed to checkout text";
	return $proceed_to_checkout;
}

// when you have a RFQ checkout setting
add_filter('gpls_woo_rfq_rfq_submit_your_order_text','gpls_woo_rfq_rfq_submit_your_order_text',10,1);

function gpls_woo_rfq_rfq_submit_your_order_text($order_button_text){

	$order_button_text = "your own submit QUOTE text ";
	return $order_button_text;
}

// when you have a normal checkout setting
add_filter('gpls_woo_rfq_checkout_submit_your_order_text','gpls_woo_rfq_checkout_submit_your_order_text',10,1);

function gpls_woo_rfq_checkout_submit_your_order_text($order_button_text){

	$order_button_text = "your own submit ORDER text ";
	return $order_button_text;
}

you can add all three.

should have worked. I tested on my copy.
The only other thing i can think is what i wrote before , your own theme or another plugin . In the future , i will add these to settings to change all these labels safely.

yes
also make sure you have the latest update.

When you turn the plugin <u>off</u> then it should have no affect on what is there. Your theme or another plugin seems to be interfering.