You need to add more full fill-ups to see consumption. 

It's not possible to export old shchema with Fuelio 3.6.0+ (2014-05-09). Database schema changes when foreign currency feature was added. Please go to Settings, try to turn on foreign currency and go to see if you can define them. If you see crash. Schema is old.

I'm saving .db backups with database version to make sure users won't import other files. 

They are quite safe. And the database schema is updating automatically. Probably you have old backup and you didn't update Fuelio from Play Store. If you will export database right now you'll see that the file will have name fuelio7.db. 

It's easy to convert old database schema to the new one. But renaming file is a bad idea. Send me your file - I can update it to the lastest version or like you said. At the moment you have old schema and for example you can't use foreign currency feature.

Yes. You had file in wrong directory. But changing name to fuelio7 will break future updates. Send me your CSV and I'll convert it to fuelio7.db (it's different schema). 

fuelio6.db is old database schema. There is new one in the lastest version. That's why CSV backups are more reliable. 

Fuelio is updating database structure while updating app and where there is a new schema. 

Why do you think it is bad when reminders are connected to costs?
I'm thinking about creating zero cost item as reminders - then you'll be able to add only reminder (without cost).

Go to Settings / Dropbox/Drive Backup and you can uncheck notification there. As I remember you shoudn't see information is everything is OK. You'll see error if you don't have for example internet connection.

Go to your Google Drive account. Check if you have Android directory there. Rename it for a moment. And then try to do backup.

This is probably permission problem to this directory.

Please, check if you didn't add wrong fill-up. Go to the bottom of the list and take a look for fill-ups you could enter by mistake trip counter as odometer counter.

It seems that you put CSV file in a wrong place. Default path for csv backups is 
/sdcard/Fuelio/backup-csv/

I don't undestand. Why do you want to change this color?