I installed the following and was able to change the fonts with ease.
https://play.google.com/store/apps/details?id=com.monotype.android.font.flipfont.develop.clean
Once installed go to settings/display/fonts/font style. I'm currently running Clean_Pennition. Gloria M Stone has released a lot of great font packs so you should be able to find something you like.
I was able to use that same font pack with no trouble on my S5.
I would however like to use my own truetype font files. Found several ways to package them into an apk, which puts them in the font list with preview, but when I select one it says it's not supported. Same issue using the XDA POWER FONTS package (I didn't try all 650 of them though).
iFont worked with the font I tested (downloaded using the app) if you don't have root, it downloads an apk and installs it so you can choose it from the font style menu, but the functions to use your own font are only available in the pay version. I might have to try that. The free version lets you download up to 3 per day which is great if the ones you want are there.
EDIT: yes! that worked! Best $1.93 I've spent this week. The iFont donate version worked with my ttf font. I selected it, chose the create apk option, and went and installed the APK and was able to select my font in the menu.
