I have a computed field (store=True) in sale.order which simply shows percentage of the Total amount

the exact percentage I have defined in sale.config.settings

default_percentage = fields.Float(default_model='sale.order')

then in sale.order I use it like this:

percentage = fields.Monetary(compute='_compute_percentage', store=True)       
def _compute_percentage(self):        
    percentage = self.env['ir.values'].get_default('sale.order', 'percentage')    ...

How can I update (recalculate) the field when I change the value in sale.config.settings

Right now the only way to do it is to change a line in the order and save again. I use Store=True because I use the field for sale reports