Refinancing car, how?

Spouse is upside down on their car

$23k owed, (loan was $40k, car is now worth $16k) and it’s $5 a day in interest, and we’ve stayed at owing $23k for a year. Even though we’re making payments (650 a month)

Loan is through GM financial (I know, but they went and got the car on a whim), 8.9 Apr and car was 4 years old when purchased

I am in a credit union, it’s a few hours away and I’ve thought about going in person to see if spouse should open an account there or if I should refinance with my credit. They bought it with theirs and have worse credit than me. I’m 730, they are 620-650 or so, with a repo under their belt from co-signing for a “friend”.

I have no car payments, and a line of credit for $7k and $1k. Only owe on the $1k LOC

Just wanting pointers.
I’ve tried convincing spouse to unload the car or trade to an older cheaper one so we can get a lower monthly payment, and more reliable car (this one has cost thousands in repairs, and needs more)

Thank you in advance