How can I increase overall text size of OSX El capitan?

Dear All,

I would like to increase overall text size of OSX system, for example the text menu on top, firefox tab, or excel sheet name. Is there a way to increase these text size?

Using lower resolution has problem with some apps; the apps will not display properly, some button will drop out and be unreachable/unclickable.

I become older each year, My eyesight become worse. If OsX still doesn't solve this problem. I think I will not be able to use it anymore.

Thank you

Cheerio,