Improving Reading through Frequent Exposure
Did your parents read to you when you were a child? You probably had a few favorite picture books that your mom or dad would read over and over. After a while, you probably read along, maybe reading one page, then your parent read the next, then you again. I imagine your finger moved along the sentence as you read it aloud, although whatever word your finger was underlining at any given moment might not have been the same one you were saying, because you were mostly reciting lines from memory. At least at first. But as you continued, you started matching the correct written word with the corresponding spoken word. You likely would have started doing this before you finished learning all the letters of the alphabet (and all the sounds they go with, including the sounds that come from various letter combinations). That came later. Part of learning how to read came from seeing words and hearing them pronounced over and over again until you were able to identify those written words. Later, as you learned more of the alphabet, identifying their sounds became easier because you could think of various words you'd used that included that letter (or letter combination) and expressed that sound. Then you realized you could apply that pattern to a bunch of other words. And that's how you learned to read.
It's understandable to think we should teach letters and those sounds first, then start putting them together to make words, and grow from there. But that approach was only a small fraction of how native speakers learn to read. The foundation of learning to read is exposure. It follows that we should use the same techniques for Learners of ESL, or even native-speaking children whose reading ability are behind the curve.
Some people like to make labels on post-it notes or whatever and stick them on furniture and objects all over the house or classroom. That way every time you flip on a light switch, you see the words "light switch", and eventually you'll remember it just by thinking about turning on a light. At least, that's the idea. However, there are limitations to this; namely that the static notes eventually blend into the scenery, and you stop paying attention to them even when they're right in front of you. I'd recommend shifting the location of the labels (e.g. from below the light switch to the left of it) every week or so. Our eyes are drawn toward change.
The other method I recommend is subtitles. English subtitles with English audio. Lots of people watch YouTube plenty, and most of that content is in English. Most videos also have subtitles available. (However, be aware that sometimes subtitles contain errors). If your students can understand enough of the video, then don't use the subtitles in their mother tongue, but use them in English. Do the same when showing them a movie. Subtitles can also help students to follow along if the people on the video are speaking a bit too fast.
Unlike labels around a room, subtitles are dynamic; they change every few seconds. The same line won't be repeated again and again, but individual words will be, and learners will pick-up on that. If they see a word enough, they might even anticipate hearing it if they see it in the subtitles a second before it's spoken. The more they see a word spoken and written together, the more readily they'll identify that connection in the future.
So encourage your students (or the parents of younger students) to use English subtitles with English videos whenever they watch TV, movies, or YouTube.
Of course, there are plenty of other ways to expose learners to written words. Children are often show pictures with labels, or are asked to match a label with a picture. There's no reason you couldn't do the same with adult learners (except, your choice of words might be different). Perhaps you can think of even more ideas.
Don't force your students to identify the sounds of every letter for every word. Just have them read and listen simultaneously. Do it often. This method takes time, of course, but most students will be more comfortable with it, and they'll eventually have stronger reading skills.