Hello,
When you edit a property that has a track with keys in Sequencer, that property is not committed until it is keyed into the track. This follows conventions established in other 3d packages. So, you can either enable autokey (which will key those values as soon as you make the edit), or click the add/update key button.
When you save, that temporary value is discarded, similar to when you edit a property and then change time without keying the property.
I hope that makes sense.