Now that I have reopened it, under Network Status, it is written that "Daemon is synchronized" but under "Wallet blocks remaining" I have to resynchronize with the whole >1.6M blocks.
Why is that? Will that happen every time I close the GUI?
Assuming you're using the GUI in conjunction with a Ledger device, see:
https://www.reddit.com/r/Monero/comments/9ap96g/gui_v01230_cli_v01230_both_with_direct_ledger/e62g3m7/?context=3
I have again synchronized the >1.6M blocks, I have pay attention to do the following:
[1] Exit the GUI by clicking on the x (right top).
[2] Exit the Ledger Monero app.
[3] Unplug the Ledger device.
But now I have to synchronize again the whole 1.6M blocks when I relauch the GUI
Maybe I am doing [2] wrongly, the Ledger Monero app close itself after minutes because it goes into the sleepd mode, so when I exit the GUI the Monero app is already exited. What can I do?
I am sure there is a proper Ledger procedure what to turn off first. But you can just save block chain in monerod. That is the other black window that opens beside GUI. Just click in there and type save and it will save your progress until then. No matter if you latter on do not close it properly or if it crashes by any chance.
It also save when you type exit. but then it also exit with that command