Any app developer here?

Hi,

Just wondering how long will it take for the complete newbie to learn how edit apps which is already out there and customize it for your own use?

Platform: Andriod
Functionality: reminder on certain task, share post, message

Any thoughts?

It really depends on your current knowledge and on your ability to learn that type of things. There might be different people that would learn how to do the same thing for days, weeks or months and noone can really predict that for you. But if you have the right mind for that kind of stuff, you should learn to make some basic changes to existing code relatively easily as long as what you want to change is something basic enough. My advice would be to find a video course on that and start learning it properly since it's just a valuable skill to have anyway and soon enough (probably way before you have finished the course) you will be able to edit what you wanted. Learning to code is usually a good investment for anyone.