Hi @MatasMo
You can do that directly in code by using this trick
Go to snippet/section file from where this text is coming
and use liquid code like this
{% if product.handle == "Your specific product handle" %}
new text
{% else %}
Same as it is currently now
{% endif %}
You should have some knowledge of liquid to do that
The text can be in product.liquid, product-template.liquid or product-form.liquid file
Keep other text same just change quantity text conditionally
Thank you!