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-> There is also 1 especial point that I am confuse yet: Some people say they faced problems trying to recover the coins from a really old electrum wallet... why is that? what do I have to do for not having this problem in 10 years from now?
Usually they tried to do something creative in terms of generating the wallet and didn't realize that they were making something non standard that would not work later.
If you just created a wallet with electrum, backed up your seed safely, made sure the seed works you will be fine.
If you try to do something 'your way' and forget exactly how you did it 10 years from now, you might not be able to get access to your wallet.
-Dave