For hearing-impaired users

I have been looking for an app to assist an older hearing-impaired man with everyday communication. This app has potential, but would benefit from two changes.
1) need an option to change the display to a larger font size, black text on white background;
2) would consider paying for an ad-free version if it meets my needs.
Thanks!

Mark W <"(((>< about Voice to Text - Speak Translate Recorder, v1.0