Need some help about VPN clients Routing

Hello Everyone
This my setup
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i’d like to achieve this with Mikrotik
Route VPN client 1 via —> wan 1
Route VPN client 2 via —> wan 2
Route VPN client 3 via —> wan 3
Route VPN client 4 via —> wan 4

my problem VPN client connection always follows the default route 1 which is one of the WANs any suggestions?
thanks

Use firewall mangles facility to route your traffic as you wish…