Fix a bug in a simple android app

Hi, I’m not a programmer. I’m a doctor and I work with children who have difficulties learning to read (Dyslexia). To help these children I’ve had an android app developed which runs on the Google app store and Amazon Fire tablets. The app is free and is called Read-it. Attached are 2 videos (each less than 20 seconds) which show the problem. Video 1 will show you what the app does on an iPad tablet. You will see that when a child touches a word that single word is read aloud. Video 2 shows the bug on the android version of the app, i.e., when a child touches a word the word that is actually read aloud is often not the word that was actually touched. I need this fixed and I have the source code for the app. The overall purpose of the app is that if a child with dyslexia has difficulty reading a word on an android tablet all they need do is touch the word and it will be immediately read aloud so they can carry on reading without interruption and help them understand the text. Also, the current android version will only work on PDFs. But, where possible, I’d like it to work on other files, particularly Kindle books and eBooks. If you apply for the project please mention that you have seen the videos so I can be confident you know what I need done.