Can I use a cheap onward flight as proof of exit from Thailand on a Non-O visa?

Hello there,

I hope you are all doing well. So, here’s my situation: I booked a flight months ago to return to Thailand on July 26 and since I planned on getting the Non O, I booked the cheapest return flight I could find in October, so within the 90 day limit (I didn’t plan on using this return flight as I will apply for the retirement visa). Now, it looks like I can return to Thailand a couple of weeks sooner so, I can easily and inexpensively change the flight to Thailand however, to change the return flight would be very expensive. Question: Can I keep the return flight date as it is (which would mean more than 90 days) and book a cheap onward flight just to show the airlines that I will exit Thailand within those 90 days or will they want this same ticket to show a return flight within the 90 days? If it is possible to use a cheap onward flight ticket as proof of exit, how many weeks/months in advance can it be booked? I would need to book it at least two months before I use it.

Has anyone does this before recently?

The option Singapore Airlines gave me was to cancel this flight, get an almost full refund and then book another flight, but it would cost me a lot more than the ticket I have now because I booked it way back in February. Of course, if that is the only/best option, I will do it. I look forward to reading your suggestions.

Thanks for your expertise.

Have a great day. Stay cool if you’re in Thailand at the moment.