Bar changes length

It is by no means clear from the screenshot what the problem is.

Can you attach the actual score?

I see what you mean in bar 66. The staff lines and bar lines are thicker. I find it usually happens when you double-click on an item to edit it, and then exit edit mode. I see it especially when I accidentally double-click on a note and then click in a blank space to exit edit mode. It's a visual distraction but nothing major.

I'm not totally understanding the problem either, and yes, posting the actual score is almost always better than a picture.

There is indeed the visual glitch of some lines appearing thicker temporarily, but that has nothing to do with the length of a bar, so I don't know if that's really what is being asked about here. Also, I see the spacing seems odd - the first measure is much narrower than the rest of the measures on the line, despite having the same exact rhythms in it. So it seems you have been fiddling with the "stretch" setting for some reason? Also, there appears to be no right hand margin at all, which won't work so well when you go to print this - did you deliberately change that?

But I don't see anywhere that anything is actually overlapping.