As NeuroticFish suggested, the first thing to do is to make sure th transaction is flagged as replaceable, the sole reason is to able to pump the fee if the transaction is stuck. 0.0452 mBTC is not too low for now, that will amounts to 0.0000452 BTC, but it may take a long time before your transaction will be included in a block, but it will eventually be included, but to get your transaction mined in the next block, you will need to increase the fee. You can use mempool.space to check the feerate to get your transaction included in the next block.
i dont understand for btc transfer, how much select for fee rate ?
example for transfer 8.14385 mBTC , can i select 0.0452 mBTC for fee rate ? (this transaction is true and confirming ?)
Feerate can not be in mBTC or BTC. Feerate is in sat/vbyte.
Fee is not the same as fee rate. Fee is in BTC which is feerate(sat/vbyte) multiply by vbyte
Fee= sat/vbyte*vbyte.
Fee will then be in satoshi, mBTC or BTC.
But for ease and wallet estimation, better use feerate (sat/vbyte). And use mempool.space to know the amount that can get your transaction to be included in a block fast.
Also as an advice, since you use Electrum, make sure that RBF is ON, so you can replace the transaction if it takes way too long to get confirmed.
I am not sure about electrum on desktop, but the latest release Android versions (4.1.1, and now 4.1.2) do not have any feature again to enable replace-by-fee as it is now enabled by default. If the sender is about to send the btc, it can flag it final, which means it is not replaceable. But to enable replace-by-fee, the transaction should not be flagged final. I believe this should be how it also now work on desktop versions latest release, but I am not certain about it yet.