Quote from: HCP
If it is on the "online" PC, then it would seem that your wallet is connected properly? Is the dot in the bottom right corner red, green or is it blue arrows?
It's red.To correct this, I would recommend that you click the red dot... it should open up the "Network" settings, on the "Overview" tab. You should see "Status", "Server" and "Blockchain". If status does not say something like "connected to 10 nodes", then something is definitely awry. Also, if "Blockchain" is not >= 505666 Blocks then your Electrum is not synced correctly.
In this case, I would suggest clicking the "Connection" tab, and then make sure that "Use SSL" is checked... and "Use proxy" is NOT checked. Finally, click on the "Server" tab and see if "Select server automatically" is checked. If it is, uncheck it and then double click on one of the servers in the list.
Abdussamad has written a quick guide on how to change the server here: https://bitcoinelectrum.com/how-to-switch-to-a-different-electrum-server/
(Just FYI, there is a bunch of good guides on his site related to Electrum
)Quote
Well, I am going to get rid of that second portable version 3.0.5. I have understood that I have to save/copy my old wallet file (my wallet_1); that I can install the new Installer 3.0.5. and paste my old wallet_1 the proper directory. I do not know what need to be done different on the off-line and on-line pcs. Moreover, as concerns my old wallet I never tried to sign, on the off-line pc, the verified transactions present on the watch-only pc. Does this have something to do with the "synced up you were mentioning above?
You don't need to re-sign anything, you just need your watching wallet on the Online PC to be synced up (ie. connected and showing a green dot)... Once it is connected properly, it'll find all the transactions and update the status of these transactions accordingly 
As for how to proceed, you need to decide which type of install you want... do you want to have it "installed" or continue to run from the "portable" exe... Then just set it up accordingly and try to stick to one version.
For "Installed", Simply run the 3.0.5 installer, move your old wallet into the new wallet file directory and you should be good to go
For "Portable", Simply put the 3.0.5 portable .exe into the same place as the old portable .exe and you should be good to go
NOTE: in either instance, you should make sure that you have checked the digital signatures of the version of Electrum you have downloaded.