Grace note after

Hiyya Quoc,
Well, first off, your are right. Grace notes after a regular note does not play back. However, keep in mind that MuseScore is more for notation and less for playback. A composer I follow, Thomas Goss, says that you should always write your music for performance, not for playback because playback sounds a lot different then performance music and if you write your music based on what you hear in MuseScore, it might turn out differently when performed. Hope that made sense. Anyway, if you absolutely needed to, you could tie a dotted quarter note to a sixteenth note, then add another sixteenth note, which would be the grace note pitch. After that, select those notes and it V to make it invisible. Now, click the little "2" at the top right of the screen. Then put in how you want it to look like/with a grace note instead of a sixteenth. Select these notes, go into View>Inspector>Notes>(Scroll down to "Notes" then click velocity type. It should say offset. Click offset and change it to user. Then below that click note velocity and type in 0. Hope that helps!
~TheBandGeek