Here are a few things to keep in mind when using the scanner:
If you're installing for the first time, always use a fresh spreadsheet.
Always import fresh data when you start up the scanner. The easiest way to do this is to use the "Import Data" option in the scanner addon menu. If you catch a "Data Refreshing" no worries. That is completely normal and you happened to import while the backend data was refreshing. Try again in 1-5 minutes.
If you are going to make changes to your data filters turn OFF the sparkline charts in the last column on the right hand side. It will load much faster. Google Sheets doesn't allow charts like that to be loaded as one column currently, so each cell has to be rendered which takes up more time than just turning them off and back on once you're done changing your filters.
If you want to see just 1 coin, use the Coin Search option. Whenever you change exchanges, the coin list should update. Sometimes it will take 10-15 seconds though before the sheet will actually load in the data. Best practice is to just let it load for a bit before you go editing things right after you change exchanges. Remember, there's a lot of data it's processing through. Also note that when you want to return to seeing all coins, you can simply just select the Coin Search cell and hit Delete to clear the cell. Sometimes you have to do this twice though for it to actually clear. I'm not entirely sure why to be honest, sometimes it just happens. If you change exchanges though, it will clear that cell as well and then load in the new coins.
Sometimes you may see data initially, but then it disappears. This isn't in reference to the "Data Refreshing" scenario, but when you made a change to the spreadsheet and you initially saw the data, but then it randomly went away. I think this is happening because Google Sheets just bugs out sometime filtering all the data. It's a huge formula it's contending with, and sometimes I think the query bugs out. So a simple fix for this is to change your Near 24h low % 1% lower and then back to where you had it. This will effectively "refresh" the page.
The color coding is really there for two reasons: to help newer traders distinguish the difference between some possible trades, and also to help guide your eyes. Generally speaking, green means a "safer" situation, yellow means caution, and red means something definitely just happened with the coin so it will be more risky. Please keep in mind though that just because something is color coded, it doesn't mean go ahead and trade the coin. For instance, just because a row is green across the board, that doesn't automatically mean a safe trade and guaranteed profits. You will still need to decipher the coins past and how the current situation relates to it. Consider the color coding inline with movement.
Are the gray rows not good coins to trade?
Not necessarily. They just don't meet any of the other color coded criteria to light up. Every coin and chart is different and thus it is still up to the trader to decide what they want to do. If you see something that peaks your interest, no matter the color, check it out. The colors are simply based on different movement ranges and if a coin is within that range, it lights up to the respective color.