Yeah, they did something horrible to their charts recently. Try Google finance. Among other things, it shows live data for several exchanges on which Yahoo only gives a fifteen minute delayed feed. Can be quite handy if you're trying to pick your moment for a trade. Some exchanges also have their own sites.
I use Yahoo Finance... what charts do you/did you (both) run before? All I look at is the current valuation, fed into Excel since I can't run each share in Euro, rather than native currency.
I had been using Yahoo Finance but their chart format changed a while back. Also they are 15 minutes behind for exchanges like LSE. I still use Yahoo for a home-grown dashboard I wrote in JavaScript -- they have a (no longer documented, but still working) API that lets me get charts of any desired size. I put up 20 or so small charts on the screen simultaneously. But for checking in detail I use Google Finance which is more up to the minute, and easier to read.
True, Yahoo Finance was really good until 6 months ago, then they did many changes and it's now almost unusable , probably due to the mess that Yahoo is in at the moment with the botched acquisition by Verizon