For pricing up option, I like using kayak.com... It gives you so many options and is a secure site for any payment information. Most airlines will charge you something if you change your plans. I know domestically in the US it is around the $150 to make a change. Refundable ticket generally cost considerably more if you can find them. Good luck..

Ps I travel for work to two different cities across the US every month via air travel. We have a corporate travel website that we need to book through, but for finding my best date/time options I use kayak.com every now and then. It helped me to save about $350 on my flight tickets for my trip in just over a month. I just changed the day I was returning and dollars were saved.

Ppss don't wait too long to book. There is definitely a prime time window to order. Too too. And they are what I call "list price". Within a month of the travel dates and it can start to sell out and prices can go sky high...

Farewell - June 4, 2020