Assign specific WAN interface to LAN ip address

Hello
I have two ISP’s as WAN interfaces (192.168.2.2 WAN1 & 192.168.3.2 WAN2) in the first two ports
and bridged other ports to LAN (192.168.1.1/24)
I have configured that all LAN can use traffic from both WAN1 & WAN2

NOW I want to make a specific lan address (192.168.1.50) to be assigned only to WAN1 to consume from a specific ISP
and keep all other LAN assigned to both WAN1 & WAN2.

Thanks in advance

How are users currently assigned to wan1 and wan2 ??

Dual WAN load balancing BY NTH method

Not familiar with that as most either use
a. Failover
b. PCC balancing see discher MUM - https://mum.mikrotik.com/presentations/US12/steve.pdf
c. Bandwidth Based Load based balancing see Tomas MUM - https://mum.mikrotik.com/presentations/US12/tomas.pdf

Post the config on the router…