How to improve the accuracy of model?

I trained with
When I used default parameters i.e. 15 epoch, 2 layers in encoding and decoding I got this result
Train perplexity: 13.3963
Train accuracy: 51.4974
Validation perplexity: 23.7748
Validation accuracy: 44.4444
Decaying learning rate to 0.00195312

Then I just increased epoch to 20, I got this result

Train perplexity: 9.47539
Train accuracy: 55.3315
Validation perplexity: 15.8719
Validation accuracy: 48.6111
Decaying learning rate to 0.00012207

When I used 20 epoch and 4 encoder and decoder
after completing 15 epcoch when I see the accuracy, it is lessed compare to previous two model?

Which paramters tunng can improve significant?

hi kari,
can you please provide us your contact through mail.
i am working on translation thing, so need your help.