in a few days I have trouble posting in steemit via esteem app.
it turns out after checking the server there is a problem.
after fixing it I can post again via esteem.well now I will share the way to my you all.
first open the main menu of esteem application
then click on the settings menu 
then click on the server 
.
change server to
the last step click confirm.
after that you can post again on your blog.
good luck stemians