Just started with bitcoin, why are my 2 transactions still pending and what does 'bump' mean?

Hey folks First off, sorry for my English, it's not my first language So, 3 days ago, I tried to transfer €0.50 in BTC from my Trezor wallet to another Trezor wallet (the one with the passphrase) just to test things out. However, I set the fees to the lowest possible, and now that transaction is still hanging in "not-confirmed" status. Then I went ahead and sent €7k in BTC to that hidden wallet (with the passphrase) this time using normal fees. I noticed we have the option to "bump" the fees, which means I can increase them to speed up the transaction. When I click on the first transaction to boost the fees, I get this message: "This operation will remove the following transactions from the mempool" and it mentions that "Chained transactions are created from the output of this initial transaction." This leads to the second transaction. But when I try to bump just the second transaction, it doesn't give me that warning. Can anyone explain this? I'm a bit worried I'll mess something up. What happens to the second transaction if I bump the first one? Will it just get canceled and come back to my wallet? Or if I only bump the second one, what happens? Thanks a lot!

In your first your transaction, you created two outputs. One was €0.50 worth of bitcoin being sent to your hidden wallet and the other one was the change sending back the remaining balance to your main wallet. In your second transaction, you spent the change received in the first transaction. If you bump the fee of the first transaction, you would replace it with a new one paying higher fee and that would invalidate the second transaction. If the fee paid for the second transaction is high enough, both transactions will be confirmed simultaneously.

Thanks you for your rapid response If i understand : So if i bump the first tx, the second one is just cancelled and my coins will be back If my second tx is confirmed, the first one will be confirmed, so i can only bump the second one ?

Yes. That is better if you do not want to invalidate the second transaction by increasing the fee for the first transaction. If you want both transactions to be confirmed at ones, pump the second transaction with the fee that would be enough to get the two transactions confirmed.

Yes, it would be like that the second transaction has not been made at all. Again right. Your second transactions is spending the fund received in the first transaction and that can be confirmed only if the first one is confirmed too. If the fee paid for the second transaction is high enough, miners will include both transactions in the same block.

A big thanks to both of you I will just wait cause the second TX will be confirmed soon

Are you sure of that? It may worth mentioning that what matters now for miners is the effective fee rate, not only the fee rate you used for the second transaction. The effective fee rate is equal to the total fee you paid for two transactions divided by their total size.

You should be watching the effective fee rate of your second transaction which might be lot less since you used 1sat/vb for the parent transaction. Bumping fee will get your transaction to be confirmed or you may have to wait longer than you anticipated.

Is it safe to share TX id here ? Fiest one was 0,00001 BTC with 0,00001128 of fees (8sat/b) Second was 0,15 btc with 0,00003135 btc of (15sat/b)

Yes, you can post your transaction ID. With posting the transaction ID, you may harm your privacy, but it has nothing to do with your security. To calculate the effective fee rate, it's required to know your transactions virtual size or weight units as well. Also note that the amount of bitcoin you sent doesn't matter at all.

I just want to suggest if the 2nd transaction is still unconfirmed, if you are planning to bump the transaction and want to avoid paying more or want to save fees then you can submit the transaction to the Viabtc TX accelerator to speed up this transaction. Take note you can only submit a transaction below 500 bytes and the rate should be more than 0.0001 BTC/KB.

There's another requirement for using ViaBTC free accelerator too and that's your transaction must not have any unconfirmed parents. This means that OP can't submit any of the transactions to ViaBTC free accelerator.

Here the first TX https://btc5.trezor.io/tx/362e17a60a380359ad44a8308a159409488258fe2bcad032673a7c591db26de3 Here the second one https://btc5.trezor.io/tx/25da59a1c854f1121d4cc5f3f14774b4f83d0cb19236eb63daf9c4380610b33e Do you think i should bump the seconde one ? It's ok for me to wait even 2-3 days

The total fee paid for the transactions is 4,263 satoshi and  their total virtual size is 349 vbyte. So, the effective fee rate is 4263 / 349 = 12.2 It's not possible to know when exactly your transactions will be confirmed, but I expect them to be confirmed in the next few hours. No need to bump the fee, if you are in a hurry.

Huge thanks evryone for your help !

No need to bump the transaction both of them were mined and have two confirmations both of them were mined by F2pool at block 831,026. Next time before you broadcast or make a transaction in the future make sure to check the https://mempool.space/ for recommended fee before you send BTC to avoid this issue.