Django Signal For Updating User

View

def transfer(request):
    if request.method == 'POST':
        t_form = TransferForm(request.POST, instance=request.user.profile)
        if t_form.is_valid():
            t_form.save()
            messages.success(request, f'Amount sent!')
    else:
        t_form = TransferForm(instance=request.user.profile)
    context = locals()
    return render(request, 'transfer.html', context)

Models.py

from django.contrib.auth.models import User
from django.db.models.signals import post_save

class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    bio = models.TextField(max_length=400, default='Hi! I am new :D')
    image = models.ImageField(
        default='default.png', upload_to='profile_pics')
    balance = models.IntegerField(User, default=10)

    def __str__(self):
        return f'{self.user.username} Profile'```

class Transfer(models.Model):
    to_user = models.ForeignKey(User, related_name='receiver', on_delete=models.CASCADE)
    from_user = models.ForeignKey(User, related_name='sender', on_delete=models.CASCADE)
    amount = models.IntegerField(default=0)

    def __str_(self):
        return f'{self.to_user.username} Transfer'

def transferred(sender, instance, **kwargs):
    Transfer.to_user = User.objects.first()
    Transfer.amount = 35
    Transfer.amount += Transfer.to_user.profile.balance
    Transfer.to_user.save()

post_save.connect(transferred, sender=Transfer)

Form:

class TransferForm(forms.ModelForm):
    class Meta:
        model = Transfer
        fields = ['to_user', 'from_user', 'amount']

What's wrong here? What to do so that when I enter the transfer class fields using TransferForm, the to_user's (who is the user whom im sending the amount) balance field updates with the amount we sent?