OP deleted my post i don't know why he did this to may be prevent the truth Op you don't believe in open communication?
this wallet has some problems i signed tx offline using my private key and it said signed but showed the same unsigned tx in the box.weird.unisgned tx was of electrum wallet and it was RBF tx.I hope this time you reply me and don't delete this post.
Sorry it was an accidental delete and was in the process of messaging you about this. You can go through this thread and github and see I don't delete bad feedback.
In truth your complaint is about electrum, its is an issue that's been know about for a while, it likely won't be fixed because we handle data within the transaction in a slightly different way, although I am making presumptions here and will happily inspect your transactions to be sure. What I suggest is; instead of building a transaction using electrum and complaining that this software doesn't sign it properly, you try building and signing a transaction using only coinb.in.
Please keep us updated. Thanks.
*Edited to clarify*
I tried with coinb.in wallet first but the thing is your wallet does not allow to set custom fees.It stated what is not sent will be used as transaction fees and i had to set custom fees so i created an unsigned tx with electrum wallet RBF enabled and then wrote the unsigned hash in coinb.in offline wallet and used my private key to sign it and it stated signed but showed the same unsigned tx in box.why coinb.in wallet does not allow custom fees?