The lines on TOUCH and SPREAD trades are set by how much the price is expected to move before your trade expires. When prices are moving quickly, the lines sit further from the current price; around major economic news, when the market is often at its most volatile, they can be a good deal further away than usual.
Why volatility matters
A TOUCH trade wins if the price reaches your line, and a SPREAD trade wins if the price finishes beyond it. In a calm market the price covers less ground in a given time, so the lines sit closer; in a busy market it can travel much further, so they're placed further out. That's why the distance can differ on the same asset and expiry from one day, or even one hour, to the next.
Economic news
The sharpest moves usually come with scheduled economic releases, such as central bank interest rate decisions and US employment and inflation figures. Because the price can jump the moment the figures are published, the lines allow for the volatility expected from a release that's due before your trade expires. So they can already be further away in the run-up to the news, even when the market looks calm at the time you buy. The main releases and their usual times are listed in Trading around major economic news.
What it means for your trade
The lines you see on the chart when you buy are the lines your trade uses, and they don't move once you've bought. Your payout is fixed at entry as well. So it's worth checking where the lines are before you tap UP, DOWN, ABOVE or BELOW, especially when news is due.
HIGH/LOW trades aren't affected in this way, because a HIGH/LOW trade is judged against the price you buy at rather than a line set away from it. Synthetic indices aren't affected either: they aren't tied to any real market, so economic news has no effect on them or on their lines.
Related: How does TOUCH work? · How does SPREAD work? · Trading around major economic news · Do payouts change?